The domestic cat (Felis catus or Felis silvestris catus, informally Felis domesticus) is a small, usually furry, domesticated, carnivorous mammal. It is often called the housecat when kept as an indoor pet, or simply the cat when there is no need to distinguish it from other felids and felines. Cats are valued by humans for companionship and ability to hunt vermin and household pests(Dell 1691P battery). They are primarily nocturnal.

Cats are similar in anatomy to the other felids, with strong, flexible bodies, quick reflexes, sharp retractable claws, and teeth adapted to killing small prey. As crepuscular predators, cats use their acute hearing and ability to see in near darkness to locate prey. Not only can cats hear sounds too faint for human ears(Dell 310-6321 battery), they can also hear sounds higher in frequency than humans can perceive. This is because the usual prey of cats (particularly rodents such as mice) make high frequency noises, so the hearing of the cat has evolved to pinpoint these faint high-pitched sounds. Cats also have a much better sense of smell than humans.

Despite being solitary hunters, cats are a social species, and cat communication includes the use of a variety of vocalizations(Dell 312-0068 battery) (meowing, purring, trilling, hissing, growling and grunting) as well as pheromones and types of cat-specific body language.

Cats have a rapid breeding rate. Under controlled breeding, they can be bred and shown as registered pedigree pets, a hobby known as cat fancy. Failure to control the breeding of pet cats by spaying and neutering and the abandonment of former household pets has resulted in large numbers of feral cats worldwide(Dell 312-0078 battery), with a population of up to 60 million of these animals in the United States alone.

Since cats were cult animals in ancient Egypt, they were commonly believed to have been domesticated there, but there may have been instances of domestication as early as the Neolithic. A genetic study in 2007 revealed that all house cats are descended from as few as five female African Wildcats (Felis silvestris lybica) c. 8000 BCE, in the Middle East(Dell 312-0079 battery). Cats are currently the most popular pet in the world, now found almost everywhere in the world.

Nomenclature and etymology

The English word cat (Old English catt) is in origin a loanword, introduced to many languages of Europe from Latin cattus and Byzantine Greek κάτια, including Portuguese and Spanish gato, French chat, German Katze, Lithuanian katė and Old Church Slavonic kotka, among others(Dell 312-0305 battery). The ultimate source of the word is Afro-Asiatic, presumably from Late Egyptian čaute, the feminine of čaus "African wildcat". The word was introduced (together with the domestic animal) to the Roman Republic by the 1st century BCE. An alternative word with cognates in many languages is English puss (pussycat). Attested only from the 16th century, it may have been introduced from Dutch poes or from Low German puuskatte(Dell 312-0326 battery), related to Swedish kattepus, or Norwegian pus, pusekatt. The etymology of this word is unknown, but it appears to reflect the native Germanic name of the animal.

While wildcats are the ancestral species from which domestic cats are descended, there are several intermediate stages between domestic pet and pedigree cats and these entirely wild cats. The semi-feral cat is a cat that is not owned by any one individual(Dell 312-0518 battery), but is generally friendly to people and may be fed by several households. Feral cats are associated with human habitations and may be fed by people or forage in rubbish, but are wary of human interaction.[17]

A group of cats is referred to as a "clowder", a male cat is called a "tom" (or a "gib", if neutered), and a female is called a "molly" or "queen". The male progenitor of a cat, especially a pedigreed cat, is its "sire", and its female progenitor is its "dam"(Dell 312-0566 battery). An immature cat is called a "kitten". In medieval Britain, the word kitten was interchangeable with the word catling.

A cat whose ancestry is formally registered is called a pedigreed cat, purebred cat, or a show cat. In strict terms, a pure-bred cat is one whose ancestry contains only individuals of the same breed. A pedigreed cat is one whose ancestry is recorded, but may have ancestors of different breeds(Dell 312-0585 battery). Cats of unrecorded mixed ancestry are referred to as domestic longhairs and domestic shorthairs or commonly as random-bred, moggies, mongrels, or mutt-cats.

Taxonomy and evolution

Main article: Cat evolution

The wildcat Felis silvestris is a close relative and possible ancestor of the domestic cat.

The Felids are a rapidly evolving family of mammals that share a common ancestor only 10–15 million years ago,[18] and include, in addition to the domestic cat, lions, tigers, cougars, and many others. Within this family, domestic cats (Felis catus) are part of the genus Felis, which is a group of small cats containing seven species. (Dell 312-0831 battery) Members of the genus are found worldwide and include the Jungle Cat (Felis chaus) of southeast Asia, the African Wildcat (Felis silvestris lybica), the Chinese Mountain Cat (Felis bieti) and the Arabian Sand Cat (Felis margarita).[20]

All the cats in this genus share a common ancestor that probably lived around 6–7 million years ago in Asia.[21] Although the exact relationships within the Felidae are still uncertain, (Dell BAT30WL battery) both the Chinese Mountain Cat and the African Wildcat are close relatives of the domestic cat and are both classed as subspecies of the Wildcat Felis silvestris.[4][22] As domestic cats are little altered from wildcats, they can readily interbreed. This hybridization may pose a danger to the genetic distinctiveness of wildcat populations, particularly in Scotland and Hungary. (Dell D6400 battery)

The domestic cat was first classified as Felis catus by Carolus Linnaeus in the tenth edition of his Systema Naturae of 1758. However, because of modern phylogenetics, domestic cats are now usually regarded as another subspecies of the Wildcat Felis silvestris. This has resulted in mixed usage of the terms, as the domestic cat can be called by its subspecies name(Dell HF674 battery), Felis silvestris catus. Wildcats have also been referred to as various subspecies of F. catus,[25] but in 2003 the International Commission on Zoological Nomenclature fixed the name for wildcats as F. silvestris.[26] The most common name in use for the domestic cat remains F. catus, following a convention for domesticated animals of using the earliest (the senior) synonym proposed. (Dell N3010 battery) Sometimes the domestic cat is called Felis domesticus[27] or Felis domestica,[1] the term coined by German naturalist Johann Christian Polycarp Erxleben in 1777. These are not valid taxonomic names, and Linnaeus's binomial takes precedence.

Cats have either a mutualistic or commensal relationship with humans. However, in comparison to dogs, cats have not undergone major changes during the domestication process(Dell Inspiron N4010 battery), as the form and behavior of the domestic cat are not radically different from those of wildcats, and domestic cats are perfectly capable of surviving in the wild. This limited evolution during domestication means that domestic cats tend to interbreed freely with feral cats, which distinguishes them from other domesticated animals.[17] However, several natural behaviors and characteristics of wildcats may have preadapted them for domestication as pets. (Dell INSPIRON 1100 battery) These traits include their small size, social nature, obvious body language, love of play and relatively high intelligence; they may also have an inborn tendency towards tameness.[30]

There are two main theories about how cats were domesticated. In one, people deliberately tamed cats in a process of artificial selection, as they were useful predators of vermin.[32] However, this has been criticized as implausible, because there may have been little reward for such an effort(Dell Inspiron 1200 battery): cats generally do not carry out commands and, although they do eat rodents, other species such as ferrets or terriers may be better at controlling these pests.[4] The alternative idea is that cats were simply tolerated by people and gradually diverged from their 'wild' relatives through natural selection, as they adapted to hunting the vermin found around humans in towns and villages. (Dell Inspiron 1420 battery)

Genetics

Main article: Cat genetics

Blue-eyed cats with white fur have a high incidence of genetic deafness.[33]

The domesticated cat and its closest wild ancestor are both diploid organisms that possess 38 chromosomes[34] and roughly 20,000 genes.[35] About 250 heritable genetic disorders have been identified in cats, many similar to human inborn errors.[36] The high level of similarity among the metabolisms of mammals allows many(Dell Inspiron 1464 battery) of these feline diseases to be diagnosed using genetic tests that were originally developed for use in humans, as well as the use of cats in the study of the human diseases.

An example of a mutation that is shared among all felines, including the big cats, is a mutant chemosensor in their taste buds that prevents them from tasting sweetness, which may explain their indifference to fruits, berries, and other sugary foods. (Dell Inspiron 1564 battery) In some breeds of cats congenital deafness is very common, with most white cats (but not albinos) being affected, particularly if they also have blue eyes.[33] The genes responsible for this defect are unknown, but the disease is studied in the hope that it may shed light on the causes of hereditary deafness in humans. (Dell Inspiron 1764 battery)

Since a large variety of coat patterns exist within the various cat breeds, the cat is an excellent animal to study the coat genetics of hair growth and coloration.[41] Several genes interact to produce cats' hair color and coat patterns. Different combinations of these genes give different phenotypes. For example, the enzyme tyrosinase is needed to produce the dark pigment melanin and Burmese cats have a mutant form that is only active at low temperatures(Dell Inspiron 1520 battery), resulting in color appearing only on the cooler ears, tail and paws.[42] A completely inactive gene for tyrosinase is found in albino cats, which therefore lack all pigment.[43] Hair length is determined by the gene for fibroblast growth factor 5, with inactive copies of this gene causing long hair.[44]

The Cat Genome Project, sponsored by the Laboratory of Genomic Diversity at the U.S. National Cancer Institute Frederick Cancer Research and Development Center in Frederick(Dell Inspiron 1521 battery), Maryland, aims to help the development of the cat as an animal model for human hereditary and infectious diseases, as well as contributing to the understanding of the evolution of mammals.[38] This effort led to the publication in 2007 of an initial draft of the genome of an Abyssinian cat called Cinnamon.[35] The existence of a draft genome has led to the discovery of several cat disease genes, (Dell inspiron 1525 battery) and even allowed the development of cat genetic fingerprinting for use in forensics.

Anatomy

Main article: Cat anatomy

Diagram of the general anatomy of a male

Domestic cats are similar in size to the other members of the genus Felis, typically weighing between 4 kilograms (8 lb 13 oz) and 5 kilograms (11 lb 0 oz). However, some breeds, such as the Maine Coon, can exceed 11 kilograms (25 lb). Conversely, very small cats (less than 1.8 kilograms (3 lb 15 oz)) have been reported. The world record for the largest cat is 21.297 kilograms (Dell inspiron 1526 battery) (46 lb 15.2 oz).[47] The smallest adult cat ever officially recorded weighed around 1.36 kilograms (3 lb).[48] Cats average about 23–25 centimeters (9–10 in) in height and 46 centimeters (18.1 in) in head/body length (males being larger than females), with tails averaging 30 centimeters (11.8 in) in length.[49]

Cats have 7 cervical vertebrae like almost all mammals, 13 thoracic vertebrae (humans have 12), 7 lumbar vertebrae (humans have 5) (Dell Inspiron 1720 battery), 3 sacral vertebrae like most mammals (humans have 5 because of their bipedal posture), and a variable number of caudal vertebrae in the tail (humans retain 3 to 5 caudal vertebrae, fused into an internal coccyx).[50]:11 The extra lumbar and thoracic vertebrae account for the cat's spinal mobility and flexibility. Attached to the spine are 13 ribs, the shoulder, and the pelvis. (Dell Inspiron 2000 battery) Unlike human arms, cat forelimbs are attached to the shoulder by free-floating clavicle bones, which allow them to pass their body through any space into which they can fit their heads.[51]

Skull

The cat skull is unusual among mammals in having very large eye sockets and a powerful and specialized jaw.[52]:35 Within the jaw, cats have teeth adapted for killing prey and tearing meat. When it overpowers its prey(Dell INSPIRON 2600 battery), a cat delivers a lethal neck bite with its two long canine teeth, inserting them between two of the prey's vertebrae and severing its spinal cord, causing irreversible paralysis and death.[53] Compared to other felines, domestic cats have narrowly spaced canine teeth; which is an adaptation to their preferred prey of small rodents, which have small vertebrae.[53] The premolar and first molar together compose the carnassial pair on each side of the mouth(Dell INSPIRON 3800 battery), which efficiently shears meat into small pieces, like a pair of scissors. These are vital in feeding, since cats' small molars cannot chew food effectively.

Cats, like dogs, are digitigrades. They walk directly on their toes, with the bones of their feet making up the lower part of the visible leg.[54] Cats are capable of walking very precisely, because like all felines they directly register; that is, they place each hind paw (almost) directly in the print of the corresponding forepaw, minimizing noise and visible tracks(Dell INSPIRON 4000 battery). This also provides sure footing for their hind paws when they navigate rough terrain. Unlike most mammals, when cats walk, they use a "pacing" gait; that is, they move the two legs on one side of the body before the legs on the other side. This trait is shared with camels and giraffes. As a walk speeds up into a trot, a cat's gait will change to be a "diagonal" gait, similar to other mammals: the diagonally opposite hind and forelegs will move simultaneously. (Dell Inspiron 5000 battery)

Like almost all members of the Felidae family, cats have protractable claws.[56] In their normal, relaxed position the claws are sheathed with the skin and fur around the toe pads. This keeps the claws sharp by preventing wear from contact with the ground and allows the silent stalking of prey. The claws on the forefeet are typically sharper than those on the hind feet. (Dell INSPIRON 500M battery)Cats can voluntarily extend their claws on one or more paws. They may extend their claws in hunting or self-defense, climbing, "kneading", or for extra traction on soft surfaces. Most cats have five claws on their front paws, and four on their rear paws.[58] The fifth front claw (the dewclaw) is proximal to the other claws. More proximally, there is a protrusion which appears to be a sixth "finger"(Dell INSPIRON 5100 battery). This special feature of the front paws, on the inside of the wrists, is the carpal pad, also found on the paws of big cats and dogs. It has no function in normal walking, but is thought to be an anti-skidding device used while jumping. Some breeds of cats are prone to polydactylyism, and may have eight or even ten toes.[58] These are particularly common along the North-East coast of North America. (Dell INSPIRON 510M battery)

Physiology

As cats are familiar and easily kept animals, their physiology has been particularly well studied; it generally resembles that of other carnivorous mammals but displays several unusual features probably attributable to cats' descent from desert-dwelling species.[27] For instance, cats are able to tolerate quite high temperatures: humans generally start to feel uncomfortable when their skin temperature passes about 44.5 °C (112 °F) (Dell INSPIRON 6000 battery), but cats show no discomfort until their skin reaches around 52 °C (126 °F),[52]:46 and can tolerate temperatures of up to 56 °C (133 °F) if they have access to water.[61]

Cats conserve heat by reducing the flow of blood to their skin and lose heat by evaporation through their mouth. They do not sweat, and pant only at very high temperatures.[62] Unusually, a cat's body temperature does not vary throughout the day; this is part of cats' general lack of circadian rhythms and may reflect their tendency to be active both during the day and at night. (Dell INSPIRON 600M battery) Cats' feces are usually dry and their urine is also highly concentrated, both of which are adaptations that allow cats to retain as much fluid as possible.[27] Their kidneys are so efficient that cats can survive on a diet consisting only of meat, with no additional water,[64] and can even rehydrate by drinking seawater.

Cats are obligate carnivores: their physiology has evolved to efficiently process meat, and they have difficulty digesting plant matter. (Dell Inspiron 6400 battery) In contrast to omnivores such as rats, which only require about 4% protein in their diet, about 20% of a cat's diet must be protein.[27] Cats are unusually dependent on a constant supply of the amino acid arginine, and a diet lacking arginine causes marked weight loss and can be rapidly fatal.[66] Another unusual feature is that the cat also cannot produce the amino acid taurine, with taurine deficiency causing macular degeneration, where the cat's retina slowly degenerates(Dell INSPIRON 7000 battery), causing irreversible blindness.[27] Since cats tend to eat all of their prey, they obtain minerals by digesting animal bones, and a diet composed only of meat may cause calcium deficiency.[27]

A cat's digestive tract is also adapted to meat eating, being much shorter than that of omnivores and having low levels of several of the digestive enzymes that are needed to digest carbohydrates.[67] These traits severely limit the cat's ability to digest and use plant-derived nutrients, as well as certain fatty acids. (Dell INSPIRON 700M battery) Despite the cat's meat-oriented physiology, several vegetarian or vegan cat foods have been marketed that are supplemented with chemically synthesized taurine and other nutrients, in attempts to produce a complete diet. However, some of these products still fail to provide all the nutrients that cats require,[68] and diets containing no animal products pose the risk of causing severe nutritional deficiencies. (Dell Inspiron 710m battery)

Senses

Main article: Cat senses

Cats have excellent night vision and can see at only one-sixth the light level required for human vision.[52]:43 This is partly the result of cat eyes having a tapetum lucidum, which reflects any light that passes through the retina back into the eye, thereby increasing the eye's sensitivity to dim light.[70] Another adaptation to dim light is the large pupils of cats' eyes. Unlike some big cats, such as tigers, domestic cats have slit pupils. (Dell INSPIRON 8200 battery) These slit pupils can focus bright light without chromatic aberration, and are needed since the domestic cat's pupils are much larger, relative to their eyes, than the pupils of the big cats.[71] Indeed, at low light levels a cat's pupils will expand to cover most of the exposed surface of its eyes.[72] However, domestic cats have rather poor color vision and (like most non-primate mammals) have only two types of cones, optimized for sensitivity to blue and yellowish green(Dell INSPIRON 8600 battery); they have limited ability to distinguish between red and green,[73] although they can achieve this in some conditions.[74]

Cats' whiskers are highly sensitive to touch.

Cats have excellent hearing and can detect an extremely broad range of frequencies. They can hear higher-pitched sounds than either dogs or humans, detecting frequencies from 55 Hz up to 79 kHz, a range of 10.5 octaves; while humans can only hear from 31 Hz up to 18 kHz, and dogs hear from 67 Hz to 44 kHz, which are both ranges of about 9 octaves. (Dell INSPIRON 9100 battery)Cats do not use this ability to hear ultrasound for communication but it is probably important in hunting,[77] since many species of rodents make ultrasonic calls.[78] Cat hearing is also extremely sensitive and is among the best of any mammal,[75] being most acute in the range of 500 Hz to 32 kHz.[79] This sensitivity is further enhanced by the cat's large movable outer ears (their pinnae), which both amplify sounds and help a cat sense the direction from which a noise is coming. (Dell INSPIRON 9200 battery)

Cats have an acute sense of smell, which is due in part to their well-developed olfactory bulb and also to a large surface of olfactory mucosa, in cats this mucosa is about 5.8 cm2 in area, which is about twice that of humans and only 1.7-fold less than the average dog.[80] Cats are very sensitive to pheromones such as 3-mercapto-3-methylbutan-1-ol, (Dell INSPIRON 9300 battery) which they use to communicate through urine spraying and marking with scent glands.[82] Cats also respond strongly to plants that contain nepetalactone, especially catnip, as they can detect that substance at less than one part per billion.[83] This response is also produced by other plants, such as Silver Vine and valerian, and may be caused by the smell of these plants mimicking a pheromone and stimulating cats' social or sexual behaviors. (Dell Inspiron 9400 battery)

Cats have relatively few taste buds compared to humans. Owing to a mutation in an early cat ancestor, one of two genes necessary to taste sweetness may have been lost by the cat family.[39] Their taste buds instead respond to amino acids, bitter tastes and acids.[85] To aid with navigation and sensation, cats have dozens of movable vibrissae (whiskers) over their body(Dell Inspiron E1505 battery), especially their face. These provide information on the width of gaps and on the location of objects in the dark, both by touching objects directly and by sensing air currents; they also trigger protective blink reflexes to protect the eyes from damage.[52]:47

Health

Main article: Cat health

The average life expectancy for male indoor cats at birth is around 12 to 14 years,[86] with females usually living a year or two longer.[87] However, there have been reports of cats reaching into their 30s,[88] with the oldest known cat, Creme Puff, dying at a verified age of 38. (Dell Inspiron E1705 battery) Feline life expectancy has increased significantly in recent decades.[90] Having a cat neutered or spayed confers some health benefits, since castrated males cannot develop testicular cancer, spayed females cannot develop uterine or ovarian cancer, and both have a reduced risk of mammary cancer.[91] The lifespan of feral cats is hard to determine accurately, although one study reported a median age of 4.7 years, with a range between 0 to 8.3 years. (Dell Inspiron Mini 9 battery)

Diseases

Cats can suffer from a wide range of health problems, including infectious diseases, parasites, injuries and chronic disease. Vaccinations are available for many of these diseases, and domestic cats are regularly given treatments to eliminate parasites such as worms and fleas.

Poisoning

In addition to obvious dangers such as rodenticides, insecticides and weed killers, cats may be poisoned by many chemicals that are usually considered safe. (Dell Latitude D400 battery) This is because their livers are less effective at some forms of detoxification than those of other animals, including humans and dogs. Some of the most common causes of poisoning in cats are antifreeze and rodent baits.[95] It has also been suggested that cats may be particularly sensitive to environmental pollutants. When a cat has a sudden or prolonged serious illness without any obvious cause, it is possible that it has been exposed to a toxin. (Dell STUDIO 1450 battery)

Human medicines should never be given to cats. For example, the painkiller paracetamol (also called acetaminophen, sold as Tylenol and Panadol) is extremely toxic to cats: even very small doses need immediate treatment and can be fatal.[97][98] Even aspirin, which is sometimes used to treat arthritis in cats, is much more toxic to them than to humans and must be administered cautiously. (Dell Vostro 1400 battery) Similarly, application of minoxidil (Rogaine) to the skin of cats, either accidentally or by well-meaning owners attempting to counter loss of fur, has sometimes been fatal.[99] Essential oils can be toxic to cats and there have been reported cases of serious illnesses caused by tea tree oil, and tea tree oil-based flea treatments and shampoos. (Dell Vostro 1500 battery)

Other common household substances that should be used with caution around cats include mothballs and other naphthalene products.[93] Phenol-based products (Pine-Sol, Dettol (Lysol) or hexachlorophene)[93] are often used for cleaning and disinfecting near cats' feeding areas or litter boxes but these can sometimes be fatal.[101] Ethylene glycol, often used as an automotive antifreeze, is particularly appealing to cats, and as little as a teaspoonful can be fatal. (Dell XPS GEN 2 battery) Some human foods are toxic to cats; for example theobromine in chocolate can cause theobromine poisoning, although few cats will eat chocolate. Large amounts of onions or garlic are also poisonous to cats.[93] Many houseplants are also dangerous,[104] such as Philodendron species and the leaves of the Easter Lily, which can cause permanent and life-threatening kidney damage. (Dell XPS M1210 battery)

Behavior

See also: Cat behavior, cat communication, cognition in cats, and cat intelligence

Free-ranging cats are active both day and night, although they tend to be slightly more active at night.[106][107] The timing of cats' activity is quite flexible and varied, which means that house cats may be more active in the morning and evening (crepuscular behavior), as a response to greater human activity at these times. (Dell XPS M1330 battery) House cats have territories that vary considerably in size, in one study ranging from seven to 28 hectares (69 acres).[107] Although they spend the majority of their time in the vicinity of their home, they can range many hundreds of meters from this central point.[107] Cats conserve energy by sleeping more than most animals, especially as they grow older. The daily duration of sleep varies, usually 12–16 hours, with 13–14 being the average(Dell XPS 1340 battery). Some cats can sleep as much as 20 hours in a 24-hour period. The term cat nap refers to the cat's ability to fall asleep (lightly) for a brief period and has entered the English lexicon—someone who nods off for a few minutes is said to be "taking a cat nap". During sleep cats experience short periods of rapid eye movement sleep accompanied by muscle twitches, which suggests that they are dreaming. (Dell XPS M1530 battery)

Sociability

Social grooming in a pair

Although wildcats are solitary, the social behavior of domestic cats is much more variable and ranges from widely dispersed individuals to feral cat colonies that form around a food source, based on groups of co-operating females. Within such groups one cat is usually dominant over the others.[112] Each cat in a colony holds a distinct territory(Dell XPS M170 battery), with sexually active males having the largest territories, which are about ten times larger than those of female cats and may overlap with several females' territories.[82] These territories are marked by urine spraying, by rubbing objects at head height with secretions from facial glands and by defecation.[82] Between these territories are neutral areas where cats watch and greet one another without territorial conflicts(Dell XPS M1710 battery). Outside these neutral areas, territory holders usually chase away stranger cats, at first by staring, hissing, and growling, and if that does not work, by short but noisy and violent attacks. Despite some cats cohabiting in colonies, cats do not have a social survival strategy, or a pack mentality and always hunt alone. (Dell XPS M1730 battery)

Domestic cats use many vocalizations for communication, including purring, trilling, hissing, growling, snarling and several different forms of meowing.[10] In contrast, feral cats are generally silent.[114]:208 Their types of body language, including position of ears and tail, relaxation of whole body, and kneading of paws, are all indicators of mood(Dell XPS M2010 battery). The tail and ears are particularly important social signal in cats, with a raised tail acting as a friendly greeting.[115][116] Tail raising also indicates the cat's position in the group's social hierarchy, with dominant individuals raising their tails less often than subordinate animals.[116] Nose-touching is also a common greeting and may be followed by social grooming, which is solicited by one of the cats raising and tilting its head. (Dell Latitude E5400 battery) However, some pet cats are poorly socialized. In particular older cats may show aggressiveness towards newly arrived kittens, which may include biting and scratching; this type of behavior is known as Feline Asocial Aggression.[117]

For cats, life in proximity with humans (and other animals kept by humans) amounts to a "symbiotic social adaptation". They may express great affection towards their human companions(Dell Latitude E5500 battery), especially if they imprint on them at a very young age and are treated with consistent affection. It has been suggested that, ethologically, the human keeper of a cat functions as a sort of surrogate for the cat's mother, and that adult domestic cats live their lives in a kind of extended kittenhood, a form of behavioral neoteny.[118] Conversely, the high-pitched purrs cats make to solicit food may mimic the cries of a hungry human infant, making them particularly hard for humans to ignore. (Dell Latitude E6400 battery)

Grooming

The hooked papillae on a cat's tongue act like a hairbrush to help clean and detangle fur.

Cats intimidate opponents by arching their backs, raising their fur, turning sideways, and hissing.

Cats are known for their cleanliness, spending many hours licking their coats.[120] The cat's tongue has backwards-facing spines about 500 micrometers long, which are called papillae. These are quite rigid, as they contain keratin. (Dell Latitude E6500 battery) These spines allow cats to groom themselves by licking their fur, with the rows of papillae acting like a hairbrush. Some cats, particularly longhaired cats, occasionally regurgitate hairballs of fur that have collected in their stomachs from grooming. These clumps of fur are usually sausage-shaped and about two to three centimeters long. Hairballs can be prevented with remedies that ease elimination of the hair through the gut(Dell Inspiron Mini 12 battery), as well as regular grooming of the coat with a comb or stiff brush.[120] Some cats can develop a compulsive behavior known as psychogenic alopecia, or excessive grooming.[122]

Fighting

With domestic cats, males are more likely to fight than females.[123] With feral cats, the most common reason for cat fighting is competition between two males to mate with a female: here most fights will be won by the heavier male. (Dell XPS M140 battery) Another possible reason for fighting in domestic cats is the difficulty of establishing territories within a small home.[123] Female cats will also fight over territory or to defend their kittens. Spaying females and neutering males will decrease or eliminate this behavior in many cases, suggesting that the behavior is linked to sex hormones(Dell XPS 13 battery).

When fighting, cats make themselves appear more impressive and threatening by raising their fur and arching their backs, thus increasing their apparent size.[115] Often, the ears are pointed down and back to avoid damage to the inner ear and potentially listen for any changes behind them while focused forward. Attacks usually comprise powerful slaps to the face and body with the forepaws as well as bites(Dell XPS 16 battery), but serious damage is rare; usually the loser runs away with little more than a few scratches to the face, and sometimes the ears. Cats will also throw themselves to the ground in a defensive posture to rake their opponent's belly with their powerful hind legs.[125]

Normally, serious injuries from fighting will be limited to infections of scratches and bites, though these can occasionally kill cats if untreated. In addition, bites are probably the main route of transmission of feline immunodeficiency virus (FIV). (Dell XPS 1640 battery) Sexually active males will usually be involved in many fights during their lives, and often have decidedly battered faces with obvious scars and cuts to the ears and nose.

Hunting and feeding

Cats feed on small prey, primarily birds and rodents.[127] Feral cats and house cats that are free-fed tend to consume many small meals in a single day, although the frequency and size of meals varies between individuals.[113] Cats use two hunting strategies, either stalking prey actively(Dell XPS 1645 battery), or waiting in ambush until an animal comes close enough to be captured. Although it is not certain, the type of strategy used may depend on the prey species in the area, with for example, cats waiting in ambush outside burrows, but tending to actively stalk birds.[128]:153

Most breeds of cat have a noted fondness for settling in high places, or perching. In the wild, a higher place may serve as a concealed site from which to hunt; domestic cats may strike prey by pouncing from such a perch as a tree branch, as does a leopard. (Dell XPS 1647 battery) Other possible explanations include that height gives the cat a better observation point, allowing it to survey its territory. During a fall from a high place, a cat can reflexively twist its body and right itself using its acute sense of balance and flexibility.[130] This is known as the cat's "righting reflex". It always rights itself in the same way, provided it has the time to do so, during a fall(Dell Latitude 131L battery). The height required for this to occur is around 90 cm (3 feet). Cats without a tail also have this ability, since a cat mostly moves its hind legs and relies on conservation of angular momentum to set up for landing, and the tail is in fact little used for this feat.[131] This leads to the proverb "a cat always lands on its feet".

Eating a house sparrow.

One poorly understood element of cat hunting behavior is the presentation of prey to human owners(Dell Latitude C400 battery). Ethologist Paul Leyhausen proposed that cats adopt humans into their social group, and share excess kill with others in the group according to the local pecking order, in which humans are placed at or near the top.[132] Anthropologist and animal scientist Desmond Morris, in his 1986 book Catwatching, suggests that when cats bring home mice or birds, they are teaching their human to hunt, or helping their human as if feeding "an elderly cat, or an inept kitten".(Dell Latitude C500 battery) Morris's theory is inconsistent with the fact that male cats also bring home prey, despite males having no involvement with raising kittens.[128]:153

Domestic cats select food based on its temperature, smell and texture, strongly disliking chilled foods and responding most strongly to moist foods rich in amino acids, which are similar to meat.[69][113] Cats may reject novel flavors (a response termed neophobia) and learn quickly to avoid foods that have tasted unpleasant in the past. (Dell Latitude C510 battery) They may also avoid sugary foods and milk; since they are lactose intolerant, these sugars are not easily digested and may cause soft stools or diarrhea. They can also develop odd eating habits. Some cats like to eat or chew on other things, most commonly wool, but also plastic, paper, string, aluminum foil/Christmas tree tinsel, or even coal. This condition is called pica and can threaten their health, depending on the amount and toxicity of the items eaten. (Dell Latitude C540 battery)

Since cats cannot fully close their lips around something to create suction, they use a lapping method with the tongue to draw liquid upwards into their mouths. Lapping at a rate of four times a second, the cat touches the smooth tip of its tongue to the surface of the water, and quickly retracts it, drawing water upwards. (Dell Latitude C600 battery)

Play

Main article: Cat play and toys

Domestic cats, especially young kittens, are known for their love of play. This behavior mimics hunting and is important in helping kittens learn to stalk, capture, and kill prey.[138] Cats will also engage in play fighting, with each other and with humans. This behavior may be a way for cats to practice the skills needed for real combat, and might also reduce any fear they associate with launching attacks on other animals. (Dell Latitude C610 battery)

Owing to the close similarity between play and hunting, cats prefer to play with objects that resemble prey, such as small furry toys that move rapidly, but rapidly lose interest (they become habituated) in a toy they have played with before.[140] Cats also tend to play with toys more when they are hungry.[141] String is often used as a toy(Dell Latitude C640 battery), but if it is eaten it can become caught at the base of the cat's tongue and then move into the intestines, a medical emergency which can cause serious illness and death.[142] Owing to the risks posed by cats eating string, it is sometimes replaced with a laser pointer's dot, which cats may chase.[143] While concerns have been raised about the safety of these lasers, Professor John Marshall(Dell Latitude C800 battery), an ophthalmologist at St Thomas' Hospital, has stated that it would be "virtually impossible" to blind a cat with a laser pointer.[144]

Reproduction

A newborn kitten

When cats mate, the tomcat (male) bites the scruff of the female's neck as she assumes a position conducive to mating known as lordosis behavior.

Female cats are seasonally polyestrous, which means they may have many periods of heat over the course of a year(Dell Latitude C810 battery), the season beginning in spring and ending in late autumn. Heat periods occur about every two weeks and last about 4 to 7 days.[145] Multiple males will be attracted to a female in heat. The males will fight over her, and the victor wins the right to mate. At first, the female will reject the male, but eventually the female will allow the male to mate. The female will utter a loud yowl as the male pulls out of her(Dell Latitude C840 battery). This is because a male cat's penis has a band of about 120–150 backwards-pointing spines, which are about one millimeter long;[146] upon withdrawal of the penis, the spines rake the walls of the female's vagina, which is a trigger for ovulation. This act also occurs to clear the vagina of other sperm in the context of a second (or more) mating, thus giving the later males a larger chance of conception. (Dell Latitude CPI battery)

After mating, the female will wash her vulva thoroughly. If a male attempts to mate with her at this point, the female will attack him. After about 20 to 30 minutes, once the female is finished grooming, the cycle will repeat.[145]

Because ovulation is not always triggered by a single mating, females may not be impregnated by the first male with which they mate. (Dell Latitude CPX battery) Furthermore, cats are superfecund; that is, a female may mate with more than one male when she is in heat, with the result that different kittens in a litter may have different fathers.[145]

The gestation period for cats is between 64–67 days, with an average length of 66 days.[148] The size of a litter averages three to five kittens, with the first litter usually smaller than subsequent litters. Kittens are weaned at between six and seven weeks(Dell Latitude D410 battery), and cats normally reach sexual maturity at 5–10 months (females) and to 5–7 months (males), although this can vary depending on breed.[145] Females can have two to three litters per year, so may produce up to 150 kittens in their breeding span of around ten years.[145]

Cats are ready to go to new homes at about 12 weeks old,[149] or when they are ready to leave their mother(Dell Latitude D420 battery). Cats can be surgically sterilized (spayed or castrated) as early as 7 weeks to limit unwanted reproduction.[150] This surgery also prevents undesirable sex-related behavior, such as aggression, territory marking (spraying urine) in males and yowling (calling) in females. Traditionally, this surgery was performed at around six to nine months of age, but it is increasingly being performed prior to puberty, at about three to six months. (Dell Latitude D430 battery) In the USA approximately 80% of household cats are neutered.[152]

Ecology

Habitats

A Black cat under the snow.

Cats are a cosmopolitan species and are found across much of the world.[29] They are extremely adaptable and are now present on all continents except Antarctica, and on 118 of the 131 main groups of islands – even on sub-Antarctic islands such as the Kerguelen Islands. Feral cats can live in forests, grasslands, tundra, coastal areas, agricultural land, scrublands, urban areas and wetlands. (Dell Latitude D500 battery) Their habitats even include small oceanic islands with no human inhabitants.[156] This ability to thrive in almost any terrestrial habitat has led to the cat's designation as one of the world's worst invasive species.[157] Despite this general adaptability, the close relatives of domestic cats, the African Wildcat (Felis silvestris lybica) and the Arabian Sand Cat (Felis margarita) both inhabit desert environments,[4] and domestic cats still show similar adaptations and behaviors. (Dell Latitude D505 battery)

Impact on prey species

Young feral cat eating a cottontail rabbit.

To date, there are few scientific data available to assess the impact of cat predation on prey populations. Even well-fed domestic cats may hunt and kill, mainly catching small mammals, but also birds, amphibians, reptiles, fish and invertebrates.[127][158] Hunting by domestic cats may be contributing to the decline in the numbers of birds in urban areas, although the importance of this effect remains controversial. (Dell Latitude D510 battery) In the wild, the introduction of feral cats during human settlement can threaten native species with extinction.[156] In many cases controlling or eliminating the populations of non-native cats can produce a rapid recovery in native animals.[160] However, the ecological role of introduced cats can be more complicated: for example, cats can control the numbers of rats(Dell Latitude D520 battery), which also prey on birds' eggs and young, so in some cases eliminating a cat population can actually accelerate the decline of an endangered bird species in the presence of a mesopredator, controlled by cats.[161]

In the Southern Hemisphere, cats are a particular problem in landmasses such as Australasia, where cat species have never been native and there were few equivalent native medium-sized mammalian predators. (Dell Latitude D600 battery) Native species such as the New Zealand Kakapo and the Australian Bettong, for example, tend to be more ecologically vulnerable and behaviorally "naive" to predation by feral cats.[163] Feral cats have had a major impact on these native species and have played a leading role in the endangerment and extinction of many animals. (Dell Latitude D610 battery)

Cat numbers in the UK are growing annually and their abundance is far above the "natural" carrying capacity, because their population sizes are independent of their prey's dynamics: i.e. cats are "recreational" hunters.[165] Population densities can be as high as 2,000 individuals per km2[166] and the current trend is an increase of 0.5 million cats annually(Dell Latitude D620 battery).

Impact on birds

The domestic cat is probably a significant predator of birds. Current UK assessments indicate that they may be accountable for an estimated 64.8 million bird deaths each year.[127] Certain species appear more susceptible than others; for example, 30% of house sparrow mortality is linked to the domestic cat.[167] In the recovery of ringed robins and dunnocks(Dell Latitude D630 battery), it was also concluded that 31% of deaths were a result of cat predation.[168] The presence of larger carnivores such as coyotes which prey on cats and other small predators reduces the effect of predation by cats and other small predators such as opossums and raccoons on bird numbers and variety.[169] The proposal that cat populations will increase when the numbers of these top predators decline is called the mesopredator release hypothesis(Dell Latitude D800 battery).

On islands, birds can contribute as much as 60% of a cat's diet.[170] In nearly all cases, however, the cat cannot be identified as the sole cause for reducing the numbers of island birds, and in some instances eradication of cats has caused a ‘mesopredator release’ effect;[171] where the suppression of top carnivores creates an abundance of smaller predators that cause a severe decline in their shared prey(Dell Latitude D810 battery). Domestic cats are, however, known to be a contributing factor to the decline of many species; a factor that has ultimately led, in some cases, to extinction. The South Island Piopio, Chatham Islands Rail,[168] the Auckland Islands Merganser,[172] and the common diving petrel[173] are a few from a long list, with the most extreme case being the flightless Stephens Island Wren, which was driven to extinction only a few years after its discovery(Dell Latitude D820 battery).

Some of the same factors that have promoted adaptive radiation of island avifauna over evolutionary time appear to promote vulnerability to non-native species in modern time. The susceptibility inherent of many island birds is undoubtedly due to evolution in the absence of mainland predators, competitors, diseases and parasites. In addition to lower reproductive rates and extended incubation periods. (Dell Latitude D830 battery)The loss of flight, or reduced flying ability is also characteristic of many island endemics.[177] These biological aspects have increased vulnerability to extinction in the presence of introduced species, such as the domestic cat.[178] Equally, behavioural traits exhibited by island species, such as "predatory naivety"[179] and ground-nesting,[176] have also contributed to their susceptibility(Dell Latitude 2100 battery).

Cats and humans

It has been suggested that this section be split into a new article. (Discuss) Proposed since March 2012.

Girl with young cat

Cats are a common companion animal in Europe and North America, and their worldwide population exceeds 500 million.[12] In 1998 there were around 43 million cats in Western Europe, 33 million in Eastern Europe, seven million in Japan and three million in Australia. (Dell Latitude 2110 battery) 2007 report stated that about 37 million US households owned cats, with an average of 2.2 cats per household giving a total population of around 82 million.[180] In contrast, there are about 72 million pet dogs in that country.[180] Although cat ownership has commonly been associated with women,[181] a 2007 Gallup poll reported that men and women were equally likely to own a cat. (Dell Latitude E4300 battery) The ratio of pedigree/purebred cats to random-bred cats varies from country to country. However, generally speaking, purebreds are less than 10% of the total population.[183]

According to the Humane Society of the United States, as well as being kept as pets, cats are also used in the international fur trade.[184] Cat fur is used in coats, gloves, hats, shoes, blankets and stuffed toys. About 24 cats are needed to make a cat fur coat. (Dell Vostro 1310 battery) This use has now been outlawed in several countries, including the United States, Australia and the European Union.[186] However, some cat furs are still made into blankets in Switzerland as folk remedies that are believed to help rheumatism.[187]

It has long been common for cats to be eaten in some parts of China and in some other Asian countries and it is estimated that in southern China's Guangdong province people eat 10,000 cats per day. (Dell Vostro 1320 battery)Animal People estimates that 4 million cats are killed and consumed in Asia every year.[189]

Domesticated varieties

Main article: Cat breed

Domesticated Indian cats sleeping

The concept of a cat breed appeared in Britain during the late 19th century.[190]:224 The current list of cat breeds is quite large: with the Cat Fanciers' Association recognizing 41 breeds, of which 16 are "natural breeds" that probably emerged before humans began breeding pedigree cats, while the others were developed over the latter half of the 20th century. (Dell Vostro 1510 battery) The owners and breeders of show cats compete to see whose animal bears the closest resemblance to the "ideal" definition and standard of the breed (see selective breeding). Because of common crossbreeding in populated areas, many cats are simply identified as belonging to the homogeneous breeds of domestic longhair and domestic shorthair, depending on their type of fur. In the United Kingdom and Australasia(Dell Vostro 1520 battery), non-purebred cats are referred in slang as moggies (derived from "Maggie", short for Margaret, reputed to have been a common name for cows and calves in 18th century England and latter applied to housecats during the Victorian era).[191] In the United States, a non-purebred cat is sometimes referred to as a barn or alley cat, even if it is not a stray(Dell Vostro 2510 battery).

A purebred chocolate Persian

Cats come in a variety of colors and patterns. These are physical properties and should not be confused with a breed of cat. Furthermore, cats may show the color and/or pattern particular to a certain breed without actually being of that breed. For example, cats may have point coloration, but not be Siamese(Dell Vostro 1014 battery).

Some original or natural breeds of cat that have a distinct phenotype that is the main type occurring naturally as the dominant domesticated cat type in their region of origin are sometimes considered as subspecies and also have received names as such in nomenclature, although this is not supported by feline biologists. Some of these cat breeds are(Dell Inspiron 1410 battery):

Manx – a stocky, solid natural breed of cat originating on the Isle of Man, characterized primarily by lack of a tail or presence of a short tail, with a dense double coat (long or short), a compact body, short, rounded back, hind legs that are visibly longer than the front legs, big bones, a wide chest, and greater depth of flank (sides of the cat nearest the rear) than other cats. (Dell Vostro 1014N battery) A female Manx usually does not weigh more than 10 pounds (4.5 kg) and a male does not weigh over 12 pounds (5.4 kg). Specific to this breed is the way their ears appear as a "cradle" when looked at from behind. Because of the genetic mutation of these cats they are susceptible of developing what is colloquially called "Manx Syndrome", a condition that could be fatal for a kitten. Although the gene normally affects only the tail, there is the risk of developmental damage to the spine, such as fused vertebrae(Dell Vostro 1015 battery).

Siamese – among the firstly recognized Oriental cats, a type of cat with a long body but an elegant posture. The length is the main characteristic based on which these cats are distinguished. Their body, legs and tail are all long and still Siamese cats are known for their grace. Also, they are famous because of their blue almond eyes and they are also called "people cats" because of the affection they show to their owners. (Dell Vostro 1015N battery)

Chartreux is a natural French breed, which is easily recognized by its size, grayish color and double coat. These cats are also famous because of the contrast between their massively built body juxtaposed with their seemingly smiling expression and sweet voice.

Turkish Angora

Coat patterns

Cat coat genetics can produce a variety of coat patterns. Some of the most common are(Dell Inspiron 1088 battery):

Blue (grey) and white bicolor cat

Bicolor, Tuxedo and Van

This pattern varies between the tuxedo cat which is mostly black with a white chest, and possibly markings on the face and paws/legs, all the way to the Van pattern (so named after the Lake Van area in Turkey, which gave rise to the Turkish Van breed), where the only colored parts of the cat are the tail (usually including the base of the tail proper) (Dell Inspiron 1088N battery), and the top of the head (often including the ears). There are several other terms for amounts of white between these two extremes, such as Harlequin or jellicle cat. Bicolor cats can have as their primary (non-white) color black, red, any dilution thereof, and tortoiseshell (see below for definition) (Dell Vostro A840 battery).

Mackerel tabby, showing the characteristic "M" on its forehead.

Tabby

Striped, with a variety of patterns. The classic blotched tabby (or marbled) pattern is the most common and consists of butterflies and bullseyes. The mackerel or striped tabby is a series of vertical stripes down the cat's side (resembling the fish). This pattern broken into spots is referred to as a spotted tabby. Finally, the tabby markings may look like a series of ticks on the fur(Dell Vostro A860 battery), thus the ticked tabby, which is almost exclusively associated with the Abyssinian breed of cats. The worldwide evolution of the cat means that certain types of tabby are associated with certain countries; for instance, blotched tabbies are quite rare outside NW Europe, where they are the most common type(Dell Vostro A860N battery).

Female tortoiseshell-and-white cat

Tortoiseshell and calico

This cat is also known as a calimanco cat or clouded tiger cat, and by the abbreviation 'tortie'. In the cat fancy, a tortoiseshell cat is patched over with red (or its dilute form, cream) and black (or its dilute blue) mottled throughout the coat. Additionally, the cat may have white spots in its fur, which make it a 'tortoiseshell and white' cat; if there is a significant amount of white in the fur and the red and black colors form a patchwork rather than a mottled aspect(Dell Inspiron Mini 1012 battery), in North America the cat will be called a calico. All calicos are tortoiseshell (as they carry both black and red), but not all tortoiseshells are calicos (which requires a significant amount of white in the fur and patching rather than mottling of the colors). The calico is also sometimes called a tricolor cat. The Japanese refer to this pattern as mi-ke (meaning "triple fur"), while the Dutch call these cats lapjeskat (SONY PCG-5G2L battery) (meaning "patches cat"). A true tricolor must consist of three colors: a reddish color, dark or light; white; and one other color, typically a brown, black, or blue.[194] Both tortoiseshell and calico cats are typically female because the coat pattern is the result of differential X chromosome inactivation in females (which, as with all normal female mammals, have two X chromosomes) (SONY PCG-5G3L battery). Conversely, cats where the overall color is ginger (orange) are commonly male (roughly in a 3:1 ratio). In a litter sired by a ginger tom, the females will be tortoiseshell or ginger. Male tortoiseshells can occur as a result of chromosomal abnormalities (often linked to sterility) or by a phenomenon known as mosaicism, where two early stage embryos are merged into a single kitten(SONY PCG-F305 battery).

Siamese cat, classical colorpoint pattern

Colorpoint

The colorpoint pattern is most commonly associated with Siamese cats, but may also appear in any domesticated cat. A colorpointed cat has dark colors on the face, ears, feet, and tail, with a lighter version of the same color on the rest of the body, and possibly some white. The exact name of the colorpoint pattern depends on the actual color, so there are seal points (dark brown) (SONY PCG-5J1L battery), chocolate points (warm lighter brown), blue points (dark gray), lilac or frost points (silvery gray-pink), red or flame points (orange), and tortie (tortoiseshell mottling) points, among others. This pattern is the result of a temperature sensitive mutation in one of the enzymes in the metabolic pathway from tyrosine to pigment, such as melanin; thus, little or no pigment is produced except in the extremities or points where the skin is slightly cooler(SONY PCG-5J2L battery). For this reason, colorpointed cats tend to darken with age as bodily temperature drops; also, the fur over a significant injury may sometimes darken or lighten as a result of temperature change.

The tyrosine pathway also produces neurotransmitters, thus mutations in the early parts of that pathway may affect not only pigment, but also neurological development. This results in a higher frequency of cross-eyes among colorpointed cats, as well as the high frequency of cross-eyes in white tigers(SONY PCG-5K2L battery).

White cats

White cat

True albinism (a mutation of the tyrosinase gene) is quite rare in cats. Much more common is the appearance of white coat color that is caused by a lack of melanocytes in the skin. A higher frequency of deafness in white cats is due to a reduction in the population and survival of melanoblast stem cells, which in addition to creating pigment-producing cells(SONY PCG-5L1L battery), develop into a variety of neurological cell types. White cats with one or two blue eyes have a particularly high likelihood of being deaf.

Smoke cats

The bottom eighth of each hair is white or creamy-white, with the rest of the hair being a solid color. Genetically this color is a non-agouti cat with the dominant inhibitor gene; a non-agouti version of the silver tabby. Smoke cats will look solid colored until they move, when the white undercoat becomes apparent. It is mostly found in pedigreed cats (especially longhair breeds) but also present in some domestic longhaired cats(SONY PCG-6S2L battery).

Body types

Cats can also come in several body types, ranging between two extremes:

Oriental

Not a specific breed, but any cat with an elongated slender build, almond-shaped eyes, long nose, large ears (the Siamese and Oriental Shorthair breeds are examples of this).

Foreign

Less slender than the oriental type, but nevertheless a cat with a slight build and generally athletic look. Typical example breeds would be the Abyssinian cat and the Turkish Angora. Some people consider the foreign and oriental body types as being the same, however(SONY PCG-6S3L battery).

Semi-Foreign

More or less the middle range of body conformation types, this type of cat is less slender without being stocky. Example breeds would be the Devon Rex and the Egyptian Mau.

Semi-Cobby

These cats look more rounded without looking too stocky. Example breeds would be the American Shorthair and British Shorthair.

Cobby

Any cat with a short, muscular, compact build, roundish eyes, short nose, and small ears. Persian cats and Exotic cats are two prime examples of such a body type(SONY PCG-6V1L battery).

Effects on human health

Because of their small size, domesticated house cats pose little physical danger to adult humans. However, in the USA cats inflict about 400,000 bites per year. This number represents about one in ten of all animal bites.[195] Many cat bites will become infected,[196] sometimes with serious consequences such as cat-scratch disease, or, more rarely, rabies. (SONY PCG-6W1L battery) Cats may also pose a danger to pregnant women and immunosuppressed individuals, since their feces can transmit toxoplasmosis.[197] A large percentage of cats are infected with this parasite, with infection rates ranging from around 40 to 60% in both domestic and stray cats worldwide. (SONY PCG-7111L battery)

Allergic reactions to cat dander and/or cat saliva are common.[201] Some humans who are allergic to cats—typically manifested by hay fever, asthma, or a skin rash—quickly acclimate themselves to a particular animal and live comfortably in the same house with it, while retaining an allergy to cats in general.[202] Whether the risk of developing allergic diseases such as asthma is increased or decreased by cat ownership is uncertain. (SONY PCG-71511M battery) Some owners cope with this problem by taking allergy medicine, along with bathing their cats frequently, since weekly bathing will reduce the amount of dander shed by a cat.[205] There have also been attempts to breed hypoallergenic cats, which would be less likely to provoke an allergic reaction. (SONY PCG-6W3L battery)

As well as posing health risks, interactions with cats may improve health and reduce physical responses to stress: for example the presence of cats may moderate increased blood pressure.[207] Cat ownership may also improve psychological health by providing emotional support and dispelling feelings of depression, anxiety and loneliness. (SONY PCG-7113L battery)Their ability to provide companionship and friendship are common reasons given for owning a cat.[182]

From another point of view, cats are thought to be able to improve the general mood of their owners by alleviating negative attitudes. According to a Swiss study carried out in 2003, cats may change the overall psychological state of their owner as their company's effect appears to be comparable to that of a human partner. (SONY PCG-7133L battery) The researchers concluded that, while cats were not shown to promote positive moods, they do alleviate negative ones.

One study found that cat ownership is associated with a reduced risk of heart attacks and strokes at the 95% confidence interval.[209]

Several studies have shown that cats develop affection towards their owners. However, the effect of these pets on human health is closely related to the time and effort the cat owner is able to invest in it, in terms of bonding and playing. (SONY PCG-7Z1L battery)

Indoor scratching

A natural behavior in cats is to periodically hook their front claws into suitable surfaces and pull backwards. This marks their territory and exercises their legs, in addition to cleaning and sharpening their claws.[211] Indoor cats benefit from being provided with a scratching post so that they are less likely to use carpet or furniture which they can easily ruin. (SONY PCG-7Z2L battery)         Commercial scratching posts typically are covered in carpeting or upholstery, but some authorities[who?] advise against this practice, as not making it clear to the cat which surfaces are permissible and which are not; they suggest using a plain wooden surface, or reversing the carpeting on the posts so that the rougher texture of the carpet backing is a more attractive alternative to the cat than the floor covering(SONY PCG-8Y1L battery). Scratching posts made of sisal rope or corrugated cardboard are also common.

Close-up of a cat's claw, with the quick clearly visible

Although scratching can serve cats to keep their claws from growing excessively long, their nails can be trimmed if necessary. Another response to indoor scratching is onychectomy, commonly known as declawing. This is a surgical procedure to remove the claw and first bone of each digit of a cat's paws. Declawing is most commonly only performed on the front feet(SONY PCG-8Y2L battery). A related procedure is tendonectomy, which involves cutting a tendon needed for cats to extend their claws.[213] Declawing is a major surgical procedure and can produce pain, infections and permanent lameness.[213]

Since this surgery is almost always performed for the benefit of owners, it is controversial and remains uncommon outside of North America.[214] In many countries, declawing is prohibited by animal welfare laws and it is ethically controversial within the veterinary community. (SONY PCG-8Z2L battery) While both the Humane Society of the United States and the American Society for the Prevention of Cruelty to Animals strongly discourage or condemn the procedure,[216] the American Veterinary Medical Association supports the procedure under certain guidelines and finds "no scientific evidence that declawing leads to behavioral abnormalities when the behavior of declawed cats is compared with that of cats in control groups." (SONY PCG-8Z1L battery) They further argue that many cats would be given up and euthanized were declawing not performed.[214] Nevertheless, many veterinarians refuse to perform the procedure.

Waste

A toilet-trained house cat

Cats bury their urine and feces. Indoor cats are usually provided with a box containing litter, typically bentonite, but sometimes other absorbent material such as shredded paper or wood chips, or sometimes sand or similar material. It should be cleaned daily and changed often, depending on the number of cats in a household and the type of litter(SONY PCG-7112L battery); if it is not kept clean, a cat may be fastidious enough to find other locations in the house for urination or defecation. This may also happen for other reasons; for instance, if a cat becomes constipated and defecation is uncomfortable, it may associate the discomfort with the litter box and avoid it in favor of another location(SONY PCG-6W2L battery).

Daily attention to the litter box also serves as a monitor of the cat's health. Bentonite or clumping litter is a variation which absorbs urine into clumps which can be sifted out along with feces, and thus stays cleaner longer with regular sifting, but has sometimes been reported to cause health problems in some cats. (SONY PCG-5K1L battery)

Some cats can be trained to use the human toilet, eliminating the litter box and its attendant expense, unpleasant odor, and the need to use landfill space for disposal. Training may involve four to six weeks of incremental moves, such as moving and elevating the litter box until it is near the toilet, as well as employing an adapter such as a bowl or small box to suspend the litter above the toilet bowl. (SONY VGP-BPS8 battery) When training is complete, the cat uses the toilet by squatting on the toilet seat over the bowl.

Feral cats

Main article: Feral cat

American feral farm cat

Feral cats are domestics cats that were born in or have reverted to a wild state. They are unfamiliar with and wary of humans and roam freely in urban and rural areas.[11] The numbers of feral cats are not known, but estimates of the US feral population range from 25 to 60 million.[11] Feral cats may live alone, but most are found in large groups called feral colonies(SONY VGP-BPS8A battery), which occupy a specific territory and are usually associated with a source of food.[220] Famous feral cat colonies are found in Rome around the Colosseum and Forum Romanum, with cats at some of these sites being fed and vetted by volunteers.[221]

Public attitudes towards feral cats vary widely: ranging from seeing them as free-ranging pets, to regarding them as vermin. (SONY VGP-BPL8 battery) One common approach to reducing the feral cat population is termed trap-neuter-return, where the cats are trapped, neutered, immunized against rabies and the feline leukemia virus, and then released. Before releasing them back into their feral colonies, the attending veterinarian often nips the tip off one ear to mark the feral as neutered and inoculated, since these cats may be trapped again(SONY VGP-BPS9 battery). Volunteers continue to feed and give care to these cats throughout their lives. Given this support, their lifespan is increased, and behavior and nuisance problems caused by competition for food are reduced.[220]

History and mythology

Main articles: Cultural depictions of cats and Cats in ancient Egypt

Egyptian sculpture at the Louvre

Traditionally, historians tended to think that ancient Egypt was the site of cat domestication, owing to the clear depictions of house cats in Egyptian paintings about 3,600 years old.[4] However, in 2004, a Neolithic grave was excavated in Shillourokambos(SONY VGP-BPS9/S battery), Cyprus, that contained the skeletons, laid close to one another, of both a human and a cat. The grave is estimated to be 9,500 years old, pushing back the earliest known feline-human association significantly. The cat specimen is large and closely resembles the African wildcat (Felis silvestris lybica), rather than present-day domestic cats. This discovery, combined with genetic studies(SONY VGP-BPS9A battery), suggest that cats were probably domesticated in the Middle East, in the Fertile Crescent around the time of the development of agriculture and then they were brought to Cyprus and Egypt.[4]

In ancient Egypt cats were sacred animals, with Bast often depicted in cat form, sometimes taking on the warlike aspect of a lioness.[190]:220 The Romans are often credited with introducing the domestic cat from Egypt to Europe; (SONY VGP-BPS9A/B battery) in Roman Aquitaine, a 1st or 2nd century epitaph of a young girl holding a cat is one of two earliest depictions of the Roman domesticated cat.[225] However, it is possible that cats were already kept in Europe prior to the Roman Empire, as they may have already been present in Britain in the late Iron Age.[32] Domestic cats were spread throughout much of the rest of the world during the Age of Discovery(SONY VGP-BPS9/B battery), as they were carried on sailing ships to control shipboard rodents and as good-luck charms.[190]:223

Freyja and her cats

Several ancient religions believed that cats are exalted souls, companions or guides for humans, that they are all-knowing but are mute so they cannot influence decisions made by humans. In Japan, the maneki neko is a cat that is a symbol of good fortune. Although there are no sacred species in Islam, some writers have stated that Muhammad had a favorite cat, Muezza. (SONY VGP-BPS9A/S battery) He is reported to have loved cats so much that "he would do without his cloak rather than disturb one that was sleeping on it".[227]

Freyja—the goddess of love, beauty, and fertility in Norse mythology—is depicted as riding a chariot drawn by cats.

Many cultures have negative superstitions about cats. An example would be the belief that a black cat "crossing your path" leads to bad luck, or that cats are witches' familiars used to augment a witch's powers and skills(SONY VGP-BPL9 battery). This led to the widespread extermination of cats in Europe in medieval times. The Black Plague was spread by fleas carried by infected rats, and the killing of cats ostensibly caused an increase in the rat population. The killing of cats in Medieval Ypres is commemorated in the innocuous present-day Kattenstoet (cat parade) (SONY VGP-BPS10 battery).

According to a myth in many cultures, cats have multiple lives. In many countries, they are believed to have nine lives, but in some Spanish-speaking regions they are said to have seven lives,[228] while in Turkish and Arabic traditions the number of lives is six.[229] The myth is attributed to the natural suppleness and swiftness cats exhibit to escape life-threatening situations. (SONY VGP-BPL10 battery)Also lending credence to this myth is the fact that falling cats often land on their feet, using an instinctive righting reflex to twist their bodies around. Nonetheless, cats can still be injured or killed by a high fall.

Frogs are amphibians in the order Anura (meaning "tailless", from Greek an-, without + oura, tail), formerly referred to as Salientia (Latin salere (salio), "to jump"). Most frogs are characterized by a short body, webbed digits (fingers or toes), protruding eyes, bifid tongue and the absence of a tail. Frogs are widely known as exceptional jumpersSony VAIO PCG-8131M battery, and many of the anatomical characteristics of frogs, particularly their long, powerful legs, are adaptations to improve jumping performance. Due to their permeable skin, frogs are often semi-aquatic or inhabit humid areas, but move easily on land. They typically lay their eggs in puddles, ponds or lakes, and their larvae, called tadpoles, have gills and tails to develop in waterSony VAIO PCG-8152M battery. Adult frogs follow a carnivorous diet, mostly of arthropods, annelids and gastropods. Frogs are most noticeable by their call, which can be widely heard during the night or day, mainly in their mating season.

The distribution of frogs ranges from tropic to subarctic regions, but most species are found in tropical rainforests. Consisting of more than 5,000 species described, they are among the most diverse groups of vertebrates. However, populations of certain frog species are declining significantlySony VAIO PCG-31311M battery.

A popular distinction is often made between frogs and toads on the basis of their appearance, but this has no taxonomic basis. (Members of the anuran family Bufonidae are called true toads, but many species from other families are also called toads.) In addition to their ecological importance, frogs have many cultural roles, such as in literature, symbolism and religion, and they are also valued as food and as petsSony VAIO PCG-31111M battery.

Etymology and terminology

The name frog derives from Old English frogga, (compare Old Norse frauki, German Frosch, older Dutch spelling kikvorsch), cognate with Sanskrit plava (frog), probably deriving from Proto-Indo-European praw = "to jump".[1]

A distinction is often made between frogs and toads on the basis of their appearance, caused by the convergent adaptation among so-called toads to dry environmentsSony VAIO PCG-8112M battery; however, this distinction has no taxonomic basis. The only family exclusively given the common name "toad" is Bufonidae, but many species from other families are also called "toads," and the species within the toad genus Atelopus are referred to as "harlequin frogs".

Taxonomy

For more details on this topic, see List of Anuran families.

The order Anura contains 4,810 species[2] in 33 families, of which the Leptodactylidae (1100 spp.), Hylidae (800 spp.) and Ranidae (750 spp.) are the richest in species. About 88% of amphibian species are frogsSony VAIO PCG-7186M battery.

European Fire-bellied Toad (Bombina bombina)

Young American bullfrog found in a stream in New Jersey

The use of the common names "frog" and "toad" has no taxonomic justification. From a taxonomic perspective, all members of the order Anura are frogs, but only members of the family Bufonidae are considered "true toads". The use of the term "frog" in common names usually refers to species that are aquatic or semi-aquatic with smooth and/or moist skinsSony VAIO PCG-7171M battery, and the term "toad" generally refers to species that tend to be terrestrial with dry, warty skin. An exception is the fire-bellied toad (Bombina bombina): while its skin is slightly warty, it prefers a watery habitat.

Frogs and toads are broadly classified into three suborders: Archaeobatrachia, which includes four families of primitive frogs; Mesobatrachia, which includes five families of more evolutionary intermediate frogsSony VAIO PCG-9Z1M battery; and Neobatrachia, by far the largest group, which contains the remaining 24 families of "modern" frogs, including most common species throughout the world. Neobatrachia is further divided into the Hyloidea and Ranoidea.[3] This classification is based on such morphological features as the number of vertebrae, the structure of the pectoral girdle, and the morphology of tadpolesSony VAIO PCG-5S1M battery. While this classification is largely accepted, relationships among families of frogs are still debated. Future studies of molecular genetics should soon provide further insights to the evolutionary relationships among anuran families.[4]

Some species of anurans hybridise readily. For instance, the Edible Frog (Rana esculenta) is a hybrid of the Pool Frog (R. lessonae) and the Marsh Frog (R. ridibunda). The fire-bellied toads Bombina bombina and Bombina variegata similarly form hybridsSony VAIO PCG-5P1M battery, although these are less fertile, giving rise to a hybrid zone.

Morphology and physiology

Skeleton of Rana esculenta showing bones of the head, vertebral column, ribs, pectoral and pelvic girdles and limbs

The morphology of frogs is unique among amphibians. Compared with the other two groups of amphibians, (salamanders and caecilians), frogs are unusual because they lack tails as adults and their legs are more suited to jumping than walkingSony VAIO PCG-5N2M battery. The physiology of frogs is generally like that of other amphibians (and differs from other terrestrial vertebrates) because oxygen can pass through their highly permeable skin. This unique feature allows frogs to respire largely through their skins.[7] The ribs are poorly developed so the lungs are filled by gulping down air. It has been shown that a frog that has been deprived of its lungs can continue living, respiring entirely through its skin. Sony VAIO PCG-3C2M battery Because the oxygen is dissolved in an aqueous film on the skin and passes from there to the blood, the skin must remain moist at all times; this makes frogs susceptible to many toxins in the environment, some of which can similarly dissolve in the layer of water and be passed into their bloodstream. This may be one of the causes of the decline in frog populationsSony VAIO PCG-8161M battery.

Many characteristics are not shared by all of the approximately 5,250 described frog species. However, some general characteristics distinguish them from other amphibians. Frogs are usually well suited to jumping, with long hind legs and elongated ankle bones. They have a short vertebral column, with no more than ten free vertebrae, followed by a fused tailbone (urostyle or coccyx), typically resulting in a tailless phenotype. Sony VAIO PCG-8141M battery

Frogs range in size from 10 mm (0.39 in) (Brachycephalus didactylus of Brazil and Eleutherodactylus iberia of Cuba) to 300 mm (12 in) (goliath frog, Conraua goliath, of Cameroon). The skin hangs loosely on the body because of the lack of loose connective tissue. Skin texture varies: it can be smooth, warty or folded. Frogs have three eyelid membranes: one is transparent to protect the eyes underwater, and two vary from translucent to opaqueSony VAIO PCG-3J1M battery. Frogs have a tympanum on each side of the head, which is involved in hearing and, in some species, is covered by skin. Most frogs have teeth, specifically pedicellate teeth in which the crown is separated from the root by fibrous tissue. Most only have teeth on the edge of the upper jaw (maxillary teeth) as well as vomerine teeth on the roof of their mouth. They do not have any teeth on their lower jawSony VAIO PCG-3H1M battery, so they usually swallow their food whole. The teeth are mainly used to hold the prey and keep it in place till they can get a good grip on it and swallow their meal, assisted by retracting their eyes into their head.[18] True toads lack any teeth at all. Some species, like the African bull frog (Pyxicephalus), which preys on relatively large organisms including mice and other frogsSony VAIO PCG-3F1M battery, have cone shaped projections of bone called odontoid processes at the front of the lower jaw which function like teeth.[2]

Feet and legs

Tyler's Tree Frog (Litoria tyleri) illustrates large toe pads and webbed feet

A bullfrog skeleton, showing elongate limb bones and extra joints. Red marks indicate bones which have been substantially elongated in frogs and joints which have become mobile. Blue indicates joints and bones which have not been modified or only somewhat elongated.

The structure of the feet and legs varies greatly among frog species
Sony VAIO PCG-3C1M battery, depending in part on whether they live primarily on the ground, in water, in trees, or in burrows. Frogs must be able to move quickly through their environment to catch prey and escape predators, and numerous adaptations help them do so.

Many frogs, especially those that live in water, have webbed toes. The degree to which the toes are webbed is directly proportional to the amount of time the species lives in the water. Sony VAIO PCG-9Z2L battery] For example, the completely aquatic African dwarf frog (Hymenochirus sp.) has fully webbed toes, whereas the toes of White's tree frog (Litoria caerulea), an arboreal species, are only a half or a quarter webbed.

A frog gripping on a palm frond

Arboreal frogs have "toe pads" to help grip vertical surfaces. These pads, located on the ends of the toes, do not work by suction. Rather, the surface of the pad consists of interlocking cells, with a small gap between adjacent cellsSony VAIO PCG-9Z1L battery. When the frog applies pressure to the toe pads, the interlocking cells grip irregularities on the substrate. The small gaps between the cells drain away all but a thin layer of moisture on the pad, and maintain a grip through capillarity. This allows the frog to grip smooth surfaces, and does not function when the pads are excessively wet. Sony VAIO PCG-9131L battery

In many arboreal frogs, a small "intercalary structure" in each toe increases the surface area touching the substrate. Furthermore, since hopping through trees can be dangerous, many arboreal frogs have hip joints that allow both hopping and walking. Some frogs that live high in trees even possess an elaborate degree of webbing between their toes, as do aquatic frogsSony VAIO PCG-8161L battery. In these arboreal frogs, the webs allow the frogs to "parachute" or control their glide from one position in the canopy to another.[21]

Ground-dwelling frogs generally lack the adaptations of aquatic and arboreal frogs. Most have smaller toe pads, if any, and little webbing. Some burrowing frogs have a toe extension—a metatarsal tubercle—that helps them to burrow. The hind legs of ground dwellers are more muscular than those of aqueous and tree-dwelling frogsSony VAIO PCG-8152L battery.

Sometimes during the tadpole stage, one of the animal's rear leg stubs is eaten by a dragonfly nymph. In some of these cases, the full leg grows anyway, and in other cases, it does not, although the frog may still live out its normal lifespan with only three legs. Other times, a parasitic flatworm called Riberoria trematodes digs into the rear of a tadpole, where it rearranges the limb bud cells, which sometimes causes the frog to have extra legs. Sony VAIO PCG-8141L battery

Jumping

Rainforest Rocket Frog jumping

Frogs are generally recognized as exceptional jumpers, and the best jumper of all vertebrates. The Australian rocket frog, Litoria nasuta, can leap over 50 times its body length (5.5 cm), resulting in jumps of over 2 meters.[23] The acceleration of the jump may be up to twice gravity. There are tremendous differences between species in jumping capabilitySony VAIO PCG-8131L battery, but within a species, jump distance increases with increasing size, but relative jumping distance (body-lengths jumped) decreases. The Indian skipper frog (Euphlyctis cyanophlyctis) has the ability to leap from the water from a position floating on the surface.[24]

While frog species can use a variety of locomotor modes (running, walking, gliding, swimming, and climbing), more are either proficient at jumping or descended from ancestors who wereSony VAIO PCG-81312L battery, with much of the musculo-skeletal morphology modified for this purpose. The tibia, fibula and tarsals have been fused into a single, strong bone, as have the radius and ulna in the forelimbs (which must absorb the impact of landing). The metatarsals have become elongated to add to the leg length and allow the frog to push against the ground for longer during a jumpSony VAIO PCG-81214L battery. The illium has elongated and formed a mobile joint with the sacrum which, in specialist jumpers such as Ranids or Hylids, functions as an additional limb joint to further power the leaps. The tail vertebrae fused into a urostyle which retracted inside the pelvis. This enabled the force to be transferred from the legs to the body during a leap. Sony VAIO PCG-81115L battery

The muscular system has been similarly modified. The hind limbs of the ancestor of frogs presumably contained pairs of muscles which would act in opposition (one muscle to flex the knee, a different muscle to extend it), as is seen in most other limbed animals. However, in modern frogs, almost all muscles have been modified to contribute to the action of jumpingSony VAIO PCG-81114L battery, with only a few small muscles remaining to bring the limb back to the starting position and maintain posture. The muscles have also been greatly enlarged, with the main leg muscles accounting for over 17% of the total mass of the frog. Slow motion photography shows that the muscles have passive flexibility. They are first stretched while the frog is still in the crouched position, then they are contracted before being stretched again to launch the frog into the airSony VAIO PCG-81113L battery. The forelegs are folded against the chest and the hind legs remain in the extended, streamlined position for the duration of the jump.[25] In some species of powerful jumpers, when the muscles contract, the energy is transferred into the stretched tendon which is wrapped around the ankle bone. Finally the muscles stretch again at the same time as the tendon releases its energy like a catapult to produce a powerful accelerations. Sony VAIO PCG-7142L battery

In some extremely capable jumpers, such as the Cuban tree frog, the peak power exerted during a jump can exceed that which the muscle is theoretically capable of producing. It is hypothesized that frogs are storing muscular energy by stretching their tendons like springs, then triggering the release all at once, allowing the frog to increase the energy of its jump beyond the limits of muscle-powered accelerationSony VAIO PCG-7141L battery. A similar mechanism has already been documented in locusts and grasshoppers.[27]

Skin

Pouched Frog (Assa darlingtoni) camouflaged against leaf litter

Microscopic view of frog skin

Being cold-blooded, frogs have to adopt behaviour patterns to regulate their temperature. To warm up they can move into the sun or onto a warm surface and to cool down they can move into the shade or adopt a stance that exposes the minimum area of skin to the air. This involves squatting down, tucking the forefeet under the chin and the hind feet under the belly. Sony VAIO PCG-71111L battery The colour of a frog's skin is used for thermo-regulation. In cool damp conditions the colour will be darker than on a hot dry day. The grey foam-nest tree frog (Chiromantis xerampelina) is even able to turn white to minimize the chance of overheating.[29]

Many frogs are able to absorb water and oxygen directly through the skin, especially around the pelvic area. However, the permeability of a frog's skin can also result in water lossSony VAIO PCG-61411L battery. Glands located all over the body exude mucous which helps keep the skin moist and reduces evaporation. Some glands on the hands and chest of males are specialized to produce sticky secretions to aid in amplexus. Similar glands in tree frogs produce a glue-like substance on the adhesive discs of the feet. Some tree frogs reduce water loss by having a waterproof layer of skin and several South American species coat their skin with a waxy secretionSony VAIO PCG-61112L battery. Others frogs have adopted behaviours to conserve water, including becoming nocturnal and resting in a water-conserving position. This posture involves the frog lying with its toes and fingers tucked under its body and chin with no gap between the body and the substrate. Some frog species will also rest in large groups with each frog pressed against its neighboursSony VAIO PCG-61111L battery. This reduces the amount of skin exposed to the air or a dry surface, and thus reduces water loss. The Woodhouse's Toad (Bufo woodhousii), if given access to water after confinement in a dry location, sits in the shallows to rehydrate itself.[30] These water conservation measures only reduce water loss enough for a predominantly arboreal existence and are not suitable for arid conditionsSony VAIO PCG-5T4L battery.

Camouflage is a common defensive mechanism in frogs. Most camouflaged frogs are nocturnal, which adds to their ability to hide. Nocturnal frogs usually find the ideal camouflaged position during the day to sleep. Some frogs have the ability to change colour, but this is usually restricted to shades of one or two colours. For example, White's tree frog varies in shades of green and brownSony VAIO PCG-5T3L battery. Features such as warts and skin folds are usually found on ground-dwelling frogs, where a smooth skin would not disguise them effectively. Arboreal frogs usually have smooth skin, enabling them to disguise themselves as leaves.[citation needed]

Certain frogs change colour between night and day, as light and moisture stimulate the pigment cells and cause them to expand or contract. Sony VAIO PCG-5T2L battery

Poison

Many frogs contain mild toxins that make them unpalatable to potential predators. For example, all toads have large poison glands—the parotoid glands—located behind the eyes, on the top of the head. Some frogs, such as some poison dart frogs, are especially toxic. The chemical makeup of toxins in frogs varies from irritants to hallucinogens, convulsants, nerve poisons, and vasoconstrictorsSony VAIO PCG-5S3L battery. Many predators of frogs have adapted to tolerate high levels of these poisons. Others, including humans, may be severely affected.

Oophaga pumilio, a poison dart frog, contains numerous alkaloids which deter predators

Some frogs obtain poisons from the ants and other arthropods they eat;[31] others, such as the Australian Corroboree Frogs (Pseudophryne corroboree and Pseudophryne pengilleyi), can manufacture an alkaloid not derived from their dietSony VAIO PCG-5S2L battery.[32] Some native people of South America extract poison from the poison dart frogs and apply it to their darts for hunting,[33] although few species are toxic enough to be used for this purpose. It was previously a misconception the poison was placed on arrows rather than darts. The common name of these frogs was thus changed from "poison arrow frog" to "poison dart frog" in the early 1980sSony VAIO PCG-5S1L battery. Poisonous frogs tend to advertise their toxicity with bright colours, an adaptive strategy known as aposematism. There are at least two non-poisonous species of frogs in tropical America (Eleutherodactylus gaigei and Lithodytes lineatus) that mimic the colouration of dart poison frogs' coloration for self-protection (Batesian mimicry). Sony VAIO PCG-5R2L battery

Because frog toxins are extraordinarily diverse, they have raised the interest of biochemists as a "natural pharmacy". The alkaloid epibatidine, a painkiller 200 times more potent than morphine, is found in some species of poison dart frogs. Other chemicals isolated from the skin of frogs may offer resistance to HIV infection.[36] Arrow and dart poisons are under active investigation for their potential as therapeutic drugs. Sony VAIO PCG-5R1L battery

The skin secretions of some toads, such as the Colorado River toad and cane toad, contain bufotoxins, some of which, such as bufotenin, are psychoactive, and have therefore been used as recreational drugs. Typically, the skin secretions are dried and smoked. Skin licking is especially dangerous, and appears to constitute an urban myth. See psychoactive toadSony VAIO PCG-5P4L battery.

Respiration and circulation

The skin of a frog is permeable to oxygen and carbon dioxide, as well as to water. There are a number of blood vessels near the surface of the skin. When a frog is underwater, oxygen is transmitted through the skin directly into the bloodstream. On land, adult frogs use their lungs to breathe. Their lungs are similar to those of humans, but the chest muscles are not involved in respirationSony VAIO PCG-5P2L battery, and there are no ribs or diaphragm to support breathing. Frogs breathe by taking air in through the nostrils (which often have valves which close when the frog is submerged), causing the throat to puff out, then compressing the floor of the mouth, which forces the air into the lungs. In August 2007 an aquatic frog named Barbourula kalimantanensis was discovered in a remote part of IndonesiaSony VAIO PCG-5N4L battery. The Bornean Flat-headed Frog (B. kalimantanensis) is the first species of frog known to science without lungs.

Frogs are known for their three-chambered heart, which they share with all tetrapods except birds, crocodilians and mammals.[38] In the three-chambered heart, oxygenated blood from the lungs and de-oxygenated blood from the respiring tissues enter by separate atriaSony VAIO PCG-5N2L battery, and are directed via a spiral valve to the appropriate vessel—aorta for oxygenated blood and pulmonary artery for deoxygenated blood. This special structure is essential to keeping the mixing of the two types of blood to a minimum, which enables frogs to have higher metabolic rates, and to be more active than otherwise.

Some species of frog have remarkable adaptations that allow them to survive in oxygen deficient waterSony VAIO PCG-51513L battery. The lake titicaca frog (Telmatobius culeus) is one such species and to survive in the poorly oxygenated waters of Lake Titicaca it has incredibly wrinkly skin that increases its surface area to enhance gas exchange. This frog will also do 'push-ups' on the lake bed to increase the flow of water around its body.[39]

Digestion and excretion

The frog's digestive system begins with the mouth. Frogs have teeth along their upper jaw called maxillary teeth, which are used to hold food before it is swallowedSony VAIO PCG-51511L battery. These teeth are very weak, and cannot be used to chew or catch and harm agile prey. Instead, the frog uses its sticky, cleft tongue to catch flies and other small moving prey. This normally lies coiled in the mouth, free at the back and attached to the mandibles at the front. It can be shot out and retracted at great speed.[19] Some frogs have no tongue and just stuff food into their mouths with their hands. Sony VAIO PCG-51412L batteryThe eyes assist in the swallowing of food as they are able to be retracted through holes in the skull and help push food down the throat.[19] The food then moves through the oesophagus into the stomach where digestive enzymes are added and it is churned up. It then proceeds to the small intestine (duodenum and ileum) where most digestion occurs. Pancreatic juice from the pancreasSony VAIO PCG-51411L battery, and bile, produced by the liver and stored in the gallbladder, are secreted into the small intestine, where the fluids digest the food and the nutrients are absorbed. The food residue passes into the large intestine where water is absorbed and wastes are routed to the cloaca.

The excretory system is similar to that of mammals. There are two kidneys which remove urea from the blood and convert it into urine. This passes along paired ureters to the urinary bladder from which it is vented periodically into the cloaca. All bodily wastes exit the body through the cloaca and the cloacal vent. Sony VAIO PCG-51312L battery

Reproductive system

In frogs the sexes are separate. In many species the male is smaller and slimmer than the female. Males have vocal cords and make a range of croaks, particularly in the breeding season, and in some species they also have vocal sacs to amplify the sound. In the male the two testes are attached to the kidneys and sperm passes into the kidneys through fine tubes called efferent ductsSony VAIO PCG-51311L battery. They then travel through the ureters which are consequently called urinogenital ducts in the male frog. There is no penis and sperm are ejected from the cloaca directly onto the eggs that the female is laying during amplexus. The ovaries of the female frog are also beside the kidneys and the eggs pass down a pair of oviducts to the exterior. During amplexus, the firm grip of the male frog stimulates the release of eggs, usually wrapped in jelly, as spawn. Sony VAIO PCG-51211L battery

Nervous system

The frog has a highly developed nervous system which consists of a brain, spinal cord and nerves. Many parts of the frog's brain correspond with those of humans. The brain consists of two olfactory lobes, two cerebral hemispheres, a pineal body, two optic lobes, a cerebellum and a medulla oblongata. Muscular coordination and posture are controlled by the cerebellum and the medulla oblongata regulates respirationSony VAIO PCG-41112L battery, digestion and other automatic functions.[40] The relative size of the cerebrum of a frog is much smaller than that of a human. Frogs have ten cranial nerves (nerves which pass information from the outside directly to the brain) and ten pairs of spinal nerves (nerves which pass information from extremities to the brain through the spinal cord).[40] By contrast, all amniotes (mammals, birds and reptiles) Sony VAIO PCG-3A4L batteryhave twelve cranial nerves. Frogs do not have external ears; the eardrums (tympanic membranes) are directly exposed. As in all animals, the ear contains semicircular canals which help control balance and orientation. Due to their short cochlea, frogs use electrical tuning to expand their range of audible frequenciesSony VAIO PCG-3A3L battery.

Sight

The eyes of frogs are located on or near the top of the head and often project outwards as hemispherical bulges. They have a large field of view and may be the only part of an otherwise submerged frog to protrude from the water. Each eye has a closable upper and lower lid and a nictitating membrane which provides further protection, especially when the frog is swimmingSony VAIO PCG-3A2L battery. The irises come in a range of colours and the pupils in a range of shapes. The common toad (Bufo bufo) has golden irises and horizontal slit-like pupils, the red-eyed tree frog (Agalychnis callidryas) has vertical slit pupils, the poison dart frog has dark irises, the fire-bellied toad (Bombina spp.) has triangular pupils and the tomato frog (Dyscophus spp.) has circular ones. The irises of the southern toad (Anaxyrus terrestris) are patterned so as to blend in with the surrounding camouflaged skin. Sony VAIO PCG-3A1L battery

The distant vision of a frog is better than its near vision. Calling frogs will quickly become silent when they see an intruder or even his shadow but the closer an object is, the less well it is seen.[28] When a frog shoots out its tongue to catch an insect it is reacting to a small moving object that it cannot see well and must line it up precisely beforehand because it shuts its eyes as the tongue is extended. Sony VAIO PCG-394L battery Whether a frog sees in colour is debatable but it has been shown that it responds positively to blue light, perhaps because that colour is associated with bodies of water that can provide refuge when the frog feels threatened.[41]

Natural history

The life cycle of frogs, like that of other amphibians, consists of four main stages: egg, tadpole, metamorphosis and adultSony VAIO PCG-393L battery. The reliance of frogs on an aquatic environment for the egg and tadpole stages gives rise to a variety of breeding behaviours that include the well-known mating calls used by the males of most species to attract females to the bodies of water that they have chosen for breeding. Some frogs also look after their eggs—and in some cases even the tadpoles—for some time after they are laidSony VAIO PCG-391L battery.

Life cycle

Frogspawn

Frogspawn development

Tadpole of Haswell's Froglet (Paracrinia haswelli

The life cycle of a frog starts with an egg. A female generally lays gelatinous egg masses containing thousands of eggs, in water. Each anuran species lays eggs in a distinctive, identifiable manner. An example are the long strings of eggs laid by the common American toad. The eggs are highly vulnerable to predationSony VAIO PCG-384L battery, so frogs have evolved many techniques to ensure the survival of the next generation. In colder areas the embryo is black to absorb more heat from the sun, which speeds up the development. Most commonly, this involves synchronous reproduction. Many individuals will breed at the same time, overwhelming the actions of predators; the majority of the offspring will still die due to predationSony VAIO PCG-383L battery, but there is a greater chance some will survive. Another way in which some species avoid the predators and pathogens eggs are exposed to in ponds is to lay eggs on leaves above the pond, with a gelatinous coating designed to retain moisture. In these species the tadpoles drop into the water upon hatching. The eggs of some species laid out of water can detect vibrations of nearby predatory wasps or snakesSony VAIO PCG-382L battery, and will hatch early to avoid being eaten.[42] Some species, such as the Cane Toad (Bufo marinus), lay poisonous eggs to minimise predation. While the length of the egg stage depends on the species and environmental conditions, aquatic eggs generally hatch within one week. Other species go through their whole larval phase inside the eggs or the mother, or they have direct developmentSony VAIO PCG-381L battery. Unlike salamanders and newts, frogs and toads never become sexually mature while still in their larval stage.

Eggs hatch and continue life as tadpoles (occasionally known as polliwogs), which typically have oval bodies and long, vertically flattened tails. At least one species (Nannophrys ceylonensis) has tadpoles that are semi-terrestrial and live among wet rocks, but as a general rule, free living larvae are fully aquaticSony VAIO PCG-7185L battery. They lack eyelids and have a cartilaginous skeleton, a lateral line system, gills for respiration (external gills at first, internal gills later) and tails with dorsal and ventral folds of skin for swimming.[45] From pretty early onward they develop a gill pouch that covers the gills and the front legs and also the lungs are developed in an early stage as an accessory breathing organSony VAIO PCG-7184L battery. Some species which go through the metamorphosis inside the egg and hatch to small frogs never develop gills, instead there are specialised areas of skin that takes care of the respiration. Tadpoles also lack true teeth, but the jaws in most species usually have two elongate, parallel rows of small keratinized structures called keradonts in the upper jaw while the lower jaw has three rows of keradontsSony VAIO PCG-7183L battery, surrounded by a horny beak, but the number of rows can be lower or absent, or much higher.[46] Tadpoles are typically herbivorous, feeding mostly on algae, including diatoms filtered from the water through the gills. Some species are carnivorous at the tadpole stage, eating insects, smaller tadpoles, and fish. Cannibalism has been observed among tadpoles. Early developers who gain legs may be eaten by the others, so the late bloomers survive longerSony VAIO PCG-7182L battery. This has been observed in England in the species Rana temporaria (common frog).[47]

Tadpoles are highly vulnerable to predation by fish, newts, predatory diving beetles and birds such as kingfishers. Poisonous tadpoles are present in many species, such as Cane Toads. The tadpole stage may be as short as a week, or tadpoles may overwinter and metamorphose the following year in some species, such as the midwife toad (Alytes obstetricans) and the common spadefoot (Pelobates fuscus) Sony VAIO PCG-7181L battery. In the Pipidae, with the exception for Hymenochirus, the tadpoles have paired anterior barbels which make them resemble small catfish.[48]

With the exception of the base of the tail, where a few vertebral structures develop to give rise to the urostyle later in life, the tail lacks the completely solid, segmental, skeletal elements of cartilage or bony tissue that are so typical for other vertebrates, although it does contain a notochordSony VAIO PCG-7174L battery

At the end of the tadpole stage, frogs undergo metamorphosis, in which they undergo a transition into the adult form. This metamorphosis last typically only 24 hours and consists of:

Larva of the common frog Rana temporaria a day before metamorphisis

Common frog - Metamorphosis stage. Notice the deformed jaws, large eyes and the remains of the gill pouchSony VAIO PCG-7173L battery.

Young frog with tail remains after metamorphosis

Adult leopard frog

The disappearance of the gill pouch, making the front legs visible.

The transformation of the jaws into the big jaws of predatory frogs (most tadpoles are scrapers of algae or are filter feeders)

The transformation of the digestive system: the long spiral gut of the larva is being replaced by the typical short gut of a predator.

An adaptation of the nervous system for stereoscopic vision, locomotion and feeding

A quick growth and movement of the eyes to higher up the skull and the formation of eyelids.

Formation of skin glands, thickening of the skin and loss of the lateral line systemSony VAIO PCG-7172L battery

An eardrum is developed to lock the middle ear.

The disappearance of the tail is somewhat later (occurs at higher thyroxin levels) and after the tail has been resorbed the animals are ready to leave the water. The material of the tail is being used for a quick growth of the legs. The disappearing of the larval structures is a regulated process called apoptosisSony VAIO PCG-7171L battery.

Incident of frog cannibalism

After metamorphosis, young adults may leave the water and disperse into terrestrial habitats, or continue to live in the aquatic habitat as adults. Almost all species of frogs are carnivorous as adults, eating invertebrates such as arthropods, annelids and gastropods. A few of the larger species may eat prey such as small mammals, fish and smaller frogsSony VAIO PCG-7162L battery. Some frogs use their sticky tongues to catch fast-moving prey, while others capture their prey and force it into their mouths with their hands. However, there are a very few species of frogs that primarily eat plants.[49] Adult frogs are themselves preyed upon by birds, large fish, snakes, otters, foxes, badgers, coatis, and other animals. Frogs are also eaten by people (see section on uses in agriculture and research, below) Sony VAIO PCG-7161L battery.

Frogs and toads can live for many years; though little is known about their life span in the wild, captive frogs and toads are recorded living up to 40 years.[50]

Frogs from temperate climates hibernate through the winter, and 4 species are known to freeze during this time, most notably Rana sylvatica.[51]

Reproduction of frogs

Once adult frogs reach maturity, they will assemble at a water source such as a pond or stream to breed. Many frogs return to the bodies of water where they were born, often resulting in annual migrations involving thousands of frogsSony VAIO PCG-7154L battery. In continental Europe, a large proportion of migrating frogs used to die on roads, before special fences and tunnels were built for them.

Male and female Common toad (Bufo bufo) in amplexus

A Male and Female common toad in amplexus. The black strands are eggs released into open water minutes after birth.

Once at the breeding ground, male frogs call to attract a mate, collectively becoming a chorus of frogs. The call is unique to the species, and will attract females of that species. Some species have satellite males who do not call, but intercept females that are approaching a calling maleSony VAIO PCG-7153L battery.

The male and female frogs then undergo amplexus. This involves the male mounting the female and gripping her (sometimes with special nuptial pads) tightly. Fertilization is external: the egg and sperm meet outside of the body. The female releases her eggs, which the male frog covers with a sperm solution. The eggs then swell and develop a protective coatingSony VAIO PCG-7152L battery. The eggs are typically brown or black, with a clear, gelatin-like covering. Members of the West African genus Nimbaphrynoides are the only species known to be viviparous and the Tanzanian genus Nectophrynoides are the only known to be ovoviviparous: In both cases, fertilization is internal and females give birth to fully developed, small toadlets. Sony VAIO PCG-7151L battery
Sony VAIO PCG-7148L battery

Most temperate species of frogs reproduce between late autumn and early spring. In the UK, most common frog populations produce frogspawn in February, although there is wide variation in timing. Water temperatures at this time of year are relatively low, typically between four and 10 degrees Celsius. Reproducing in these conditions helps the developing tadpoles because dissolved oxygen concentrations in the water are highest at cold temperaturesSony VPCW21M2E/WI battery. More importantly, reproducing early in the season ensures that appropriate food is available to the developing frogs at the right time.

Parental care

Colour plate from Ernst Haeckel's 1904 Kunstformen der Natur, depicting frog species that include two examples of parental care.

Although care of offspring is poorly understood in frogs, it is estimated that up to 20% of amphibian species may care for their young in one way or another, and there is a great diversity of parental behaviours. Sony VPCW21C7E battery Some species of poison dart frog lay eggs on the forest floor and protect them, guarding the eggs from predation and keeping them moist. The frog will urinate on them if they become too dry. After hatching, a parent (the sex depends upon the species) will move them, on its back, to a water-holding bromeliad. The parent then feeds them by laying unfertilized eggs in the bromeliad until the young have metamorphosedSony VPCW12S1E/WZ battery. Other frogs carry the eggs and tadpoles on their hind legs or back (e.g. the midwife toads, Alytes spp.). Some frogs even protect their offspring inside their own bodies. The male Australian Pouched Frog (Assa darlingtoni) has pouches along its side in which the tadpoles reside until metamorphosis. The female Gastric-brooding Frogs (genus Rheobatrachus) from AustraliaSony VPCW12S1E/W battery, now probably extinct, swallows its tadpoles, which then develop in the stomach. To do this, the Gastric-brooding Frog must stop secreting stomach acid and suppress peristalsis (contractions of the stomach). Darwin's Frog (Rhinoderma darwinii) from Chile puts the tadpoles in its vocal sac (see next section) for development. Some species of frog will leave a 'babysitter' to watch over the frogspawn until it hatchesSony VPCW12S1E/T battery.

The evolution of parental care in frogs is driven primarily by the size of the water body in which they breed. There is an inverse relationship between the level of parental care in a frog species and the size of the body of water—frogs that breed in smaller water bodies tend to have more complex parental care behaviors. Sony VPCW12S1E/P battery Water body size shows this strong relationship with parental care because it encompasses several important variables that interact to select for parental care: predation, desiccation, competition, and resource limitation. Because predation of eggs and larvae is high in large water bodies, a number of frog species evolved terrestrial oviposition. Once eggs are deposited on landSony VPCW11S1E/W battery, the desiccating terrestrial environment demands uniparental care in the form of egg hydration to ensure egg survival.[56] The subsequent need to transport hatched tadpoles to a water source requires an even more intense form of uniparental care. In small water bodies where predators are mostly absent, such as phytotelmata (water-filled leaf axils or small woody cavities)Sony VPCW11S1E/T battery, inter-tadpole competition becomes the variable that constrains tadpole survival. Certain frogs species avoid this competition by evolving the use of smaller phytotelmata as tadpole deposition sites.[57] However, while these smaller tadpole rearing sites are free of competition, they also lack nutrients. Because they do not have sufficient nutrients to support a tadpole without parental provisioning behaviorSony VPCW11S1E/P battery, frog species that transitioned from the use of larger to smaller phytotelmata have evolved trophic (unfertilized) egg laying. In this complex form of biparental care, the female provides her offspring with nutritive eggs. While each of these variables select for different behaviors, they correlate with the size of a species' tadpole-rearing site and influence the degree of parental care displayed by a speciesSony VPCYA1S1E/B battery.

Call

A male Dendropsophus microcephalus displaying its vocal sac during its call.

The call of a frog is unique to its species. Frogs call by passing air through the larynx in the throat. In most calling frogs, the sound is amplified by one or more vocal sacs, membranes of skin under the throat or on the corner of the mouth that distend during the amplification of the call. Some frog calls are so loud, they can be heard up to a mile away. Sony VPCYA1V9E/B batteryThe field of neuroethology studies the neurocircuitry that underlies frog audition.

Some frogs lack vocal sacs, such as those from the genera Heleioporus and Neobatrachus, but these species can still produce a loud call. Their buccal cavity is enlarged and dome-shaped, acting as a resonance chamber that amplifies their call. Species of frog without vocal sacs and that do not have a loud call tend to inhabit areas close to flowing water. The noise of flowing water overpowers any call, so they must communicate by other meansSony VPCY22Z5008B battery.

The main reason for calling is to allow males to attract a mate. Males call either individually or in a group called a chorus. Females of many frog species, for example Polypedates leucomystax, produce calls reciprocal to the males', which act as the catalyst for the enhancement of reproductive activity in a breeding colony. Sony VPCY21S1E/SI batteryA male frog emits a release call when mounted by another male. Tropical species also have a rain call that they make on the basis of humidity cues prior to a rain shower. Many species also have a territorial call that is used to chase away other males. All of these calls are emitted with the mouth of the frog closedSony VPCY21S1E/L battery.

A distress call, emitted by some frogs when they are in danger, is produced with the mouth open, resulting in a higher-pitched call. The effectiveness of the call is unknown; however, it is suspected the call intrigues the predator until another animal is attracted, distracting them enough for its escapeSony VPCY21S1E/G battery.

Many species of frog have deep calls, or croaks. The English onomatopoeic spelling is "ribbit". The croak of the American bullfrog (Rana catesbiana) is sometimes spelt "jug o' rum".[60] Other examples are Ancient Greek brekekekex koax koax for probably Rana ridibunda, and the description in Rigveda 7:103.6 gómāyur éko ajámāyur ékaħ = "one has a voice like a cow's, one has a voice like a goat's"Sony VPCY11S1E/S battery.

Distribution and conservation status

The Red-eyed Tree Frog (Litoria chloris) is a species of tree frog native to eastern Australia.

See also: Decline in amphibian populations

The habitat of frogs extends almost worldwide, but they do not occur in Antarctica and are not present on many oceanic islands.[61][62] The greatest diversity of frogs occurs in the tropical areas of the world, where water is readily available, suiting frogs' requirements due to their skin. Some frogs inhabit arid areas such as deserts, where water may not be easily accessibleSony VPCY11S1E battery, and rely on specific adaptations to survive. The Australian genus Cyclorana and the American genus Pternohyla will bury themselves underground, create a water-impervious cocoon and hibernate during dry periods. Once it rains, they emerge, find a temporary pond and breed. Egg and tadpole development is very fast in comparison to most other frogs so that breeding is complete before the pond dries upSony VPCZ11X9E/B battery. Some frog species are adapted to a cold environment; for instance the wood frog (Rana sylvatica), whose habitat extends north of the Arctic Circle, buries itself in the ground during winter when much of its body freezes.[19]

Golden toad (Bufo periglenes) – last seen in 1989

Frog populations have declined dramatically since the 1950s: more than one third of species are believed to be threatened with extinction and more than 120 species are suspected to be extinct since the 1980s. Sony VPCZ11Z9E/B battery Among these species are the golden toad of Costa Rica and the Gastric-brooding frogs of Australia. Habitat loss is a significant cause of frog population decline, as are pollutants, climate change, the introduction of non-indigenous predators/competitors, and emerging infectious diseases including chytridiomycosis. Many environmental scientists believe that amphibiansSony VPCZ12M9E/B battery, including frogs, are excellent biological indicators of broader ecosystem health because of their intermediate position in food webs, permeable skins, and typically biphasic life (aquatic larvae and terrestrial adults).[64] It appears that it is the species with both aquatic eggs and aquatic larvae that are most affected by the decline, while those with direct development are the most resistant. Sony VPCZ12X9E/X battery

A Canadian study conducted in 2006, suggested heavy traffic near frog habitats as a large threat to frog populations.[66] In a few cases, captive breeding programs have been attempted to alleviate the pressure on frog populations, and these have proved successful.[67][68] In 2007, it was reported the application of certain probiotic bacteria could protect amphibians from chytridiomycosis. Sony VPCZ12Z9E/X battery One current project, The Panama Amphibian Rescue and Conservation Project, has subsequently been developed in order to rescue species at risk of chytridiomycosis in eastern Panama, and to develop field applications of this probiotic cure.[70]

Zoos and aquariums around the world named 2008 the Year of the Frog, to draw attention to the conservation issues. Sony VPCZ138GA battery

Evolution

A fossilized frog from the Czech Republic, possibly Palaeobatrachus gigas

Until the discovery of the Early Permian Gerobatrachus hottoni in 2008, a stem-batrachian with many salamander-like characteristics, the earliest known proto-frog was Triadobatrachus massinoti, from the 250 million year old early Triassic of Madagascar.[72] The skull is frog-like, being broad with large eye sockets, but the fossil has features diverging from modern amphibiaSony VPCZ13M9E/B battery. These include a different ilium, a longer body with more vertebrae, and separate vertebrae in its tail (whereas in modern frogs, the tail vertebrae are fused, and known as the urostyle or coccyx). The tibia and fibula bones are unfused and separate, making it probable Triadobatrachus was not an efficient leaper.

Another fossil frog, Prosalirus bitis, was discovered in 1995. The remains were recovered from Arizona's Kayenta Formation, which dates back to the Early Jurassic epoch, Sony VPCZ13M9E/X batterysomewhat younger than Triadobatrachus. Like Triadobatrachus, Prosalirus did not have greatly enlarged legs, but had the typical three-pronged pelvic structure. Unlike Triadobatrachus, Prosalirus had already lost nearly all of its tail[citation needed] and was well adapted for jumping.[74]

The earliest known "true frog" is Vieraella herbsti, from the early Jurassic (188–213 million years ago) Sony VPCZ13V9E battery. It is known only from the dorsal and ventral impressions of a single animal and was estimated to be 33 mm (1.3 in) from snout to vent. Notobatrachus degiustoi from the middle Jurassic is slightly younger, about 155–170 million years old. It is likely the evolution of modern Anura was completed by the Jurassic period. The main evolutionary changes involved the shortening of the body and the loss of the tailSony VPCZ13V9E/X battery.

The earliest full fossil record of a modern frog is of sanyanlichan, which lived 125 million years ago[75] and had all modern frog features, but bore 9 presacral vertebrae instead of the 8 of modern frogs.[76]

Frog fossils have been found on all continents except Antarctica, but biogeographic evidence suggests they inhabited Antarctica when it was warmer. Sony VPCZ13Z9E/X battery

Uses in agriculture and research

Cooked frog. Jianyang, Fujian, China

For more details on this topic, see Animal testing on frogs.

Frog meat less than one minute old in a market in Haikou City, Hainan Province, China

Frogs are raised commercially for several purposes. Frogs are used as a food source; frog legs are a delicacy in China, France, Indonesia, the Philippines, the north of Greece and in many parts of the American South, especially Louisiana. Dead frogs are sometimes used for dissections in high school and university anatomy classesSony VPCZ21M9E battery, often after being injected with coloured plastics to enhance the contrast between the organs. This practice has declined in recent years with the increasing concerns about animal welfare.

Frogs have served as important model organisms throughout the history of science. Eighteenth-century biologist Luigi Galvani discovered the link between electricity and the nervous system through studying frogs. The African clawed frog or platanna (Xenopus laevis) was first widely used in laboratories in pregnancy assays in the first half of the 20th centurySony VPCZ21Q9E battery. When human chorionic gonadotropin, a hormone found in substantial quantities in the urine of pregnant women, is injected into a female X. laevis, it induces them to lay eggs. In 1952, Robert Briggs and Thomas J. King cloned a frog by somatic cell nuclear transfer, the same technique later used to create Dolly the Sheep, their experiment was the first time successful nuclear transplantation had been accomplished in metazoans. Sony VPCZ21V9E battery

Frogs are used in cloning research and other branches of embryology because frogs are among the closest living relatives of man to lack egg shells characteristic of most other vertebrates, and therefore facilitate observations of early development. Although alternative pregnancy assays have been developed, biologists continue to use Xenopus as a model organism in developmental biology because it is easy to raise in captivity and has a large and easily manipulatable embryoSony VPCEH3T9E battery. Recently, X. laevis is increasingly being displaced by its smaller relative X. tropicalis, which reaches its reproductive age in five months rather than one to two years (as in X. laevis),[79] facilitating faster studies across generations. The genome sequence of X. tropicalis will probably be completed by 2015 at the latest.[80]

Cultural beliefs

For more details on this topic, see Frogs in popular culture.

Moche Frog 200 A.D. Larco Museum Collection Lima, PeruSony VPCEH3N6E battery

Frogs feature prominently in folklore, fairy tales and popular culture. They tend to be portrayed as benign, ugly, clumsy, but with hidden talents. Examples include Michigan J. Frog, The Frog Prince, and Kermit the Frog. Michigan J. Frog, featured in the Warner Brothers cartoon One Froggy Evening, only performs his singing and dancing routine for his ownerSony VPCEH3N1E battery. Once another person looks at him, he will return to a frog-like pose. "The Frog Prince" is a fairy tale of a frog who turns into a handsome prince once kissed. Kermit the Frog, on the other hand, is a conscientious and disciplined character of The Muppet Show and Sesame Street; while openly friendly and greatly talented, he is often portrayed as cringing at the fanciful behavior of more flamboyant charactersSony VPCEH3D0E battery.

The Moche people of ancient Peru worshipped animals and often depicted frogs in their art.[81] In Panama local legend promised luck to anyone who spotted a golden frog in the wild and some believed that when Panamanian Golden Frogs died, they would turn into a gold talisman, known as a huaca. Today, despite being extinct in the wildSony VPCEH3B1E battery, Panamanian Golden Frogs remain an important cultural symbol and can be found on decorative cloth molas made by the Kuna Indians, on T-shirts, as inlaid design on a new overpass in Panama City and even on lottery tickets.[82]

Owls are a group of birds that belong to the order Strigiformes, constituting 200 extant bird of prey species. Most are solitary and nocturnal, with some exceptions (e.g., the Northern Hawk Owl). Owls hunt mostly small mammals, insects, and other birdsSony VPCEH2Z1E battery, although a few species specialize in hunting fish. They are found in all regions of the Earth except Antarctica, most of Greenland and some remote islands. Though owls are typically solitary, the literary collective noun for a group of owls is a parliament. Owls are characterized by their small beaks and wide faces, and are divided into two families: the typical owls, Strigidae; and the barn-owls, TytonidaeSony VPCEH2S9E battery.

Description

Burrowing Owl (Athene cunicularia)

Owls have large forward-facing eyes and ear-holes; a hawk-like beak; a flat face; and usually a conspicuous circle of feathers, a facial disc, around each eye. The feathers making up this disc can be adjusted in order to sharply focus sounds that come from varying distances onto the owls' asymmetrically placed ear cavities. Most birds of prey sport eyes on the sides of their headsSony VPCEH2Q1E battery, but the stereoscopic nature of the owl's forward-facing eyes permits the greater sense of depth perception necessary for low-light hunting. Although owls have binocular vision, their large eyes are fixed in their sockets—as are those of other birds—so they must turn their entire head to change views. Owls can rotate their heads and necks as much as 270 degrees in either direction. Sony VPCEH2P0E batteryAs owls are farsighted, they are unable to see clearly anything within a few centimeters of their eyes. Caught prey can be felt by owls with the use of filoplumes—like feathers on the beak and feet that act as "feelers". Their far vision, particularly in low light, is exceptionally good.

The smallest owl—weighing as little as 31 grams (1 oz) and measuring some 13.5 centimetres (5 in)—is the Elf Owl (Micrathene whitneyi).[4] Around the same diminutive length, although slightly heavier, are the lesser known Long-whiskered Owlet (Xenoglaux loweryi) Sony VPCEH2N1E battery and Tamaulipas Pygmy Owl (Glaucidium sanchezi).[4] The largest owl by length is the Great Grey Owl (Strix nebulosa), which measures around 70 cm (28 in) on average and can attain a length of 84 cm (33 in).[4] However, the heaviest (and largest winged) owls are two similarly-sized eagle owls; the Eurasian Eagle-Owl (Bubo bubo) and Blakiston's Fish Owl (B. blakistoni). These two speciesSony VPCEH2M9E battery, which are on average about 2.53 cm (1.00 in) shorter in length than the Great Grey, can both attain a wingspan of 2 m (6.6 ft) and a weight of 4.5 kg (10 lb) in the largest females.

Different species of owls make different sounds; this wide range of calls aids owls in finding mates or announcing their presence to potential competitors, and also aids ornithologists and birders in locating these birds and recognizing species. As noted above, the facial disc helps owls to funnel the sound of prey to their earsSony VPCEH2M1E battery. In many species, these discs are placed asymmetrically, for better directional location.[9][verification needed]

The plumage of owls is generally cryptic, but many species have facial and head markings, including face masks, ear tufts and brightly coloured irises. These markings are generally more common in species inhabiting open habitats, and are thought to be used in signaling with other owls in low light conditions. Sony VPCEH2L9E battery

Owl eggs usually have a white color and an almost spherical shape, and range in number from a few to a dozen, depending on species. Eggs are laid at intervals of 1 to 3 days and do not hatch at the same time. This fact accounts for the wide variation in the size of sibling nestlings. Owls do not construct nests, but rather look for a sheltered nesting site or an abandoned nest in trees, underground burrows, or in buildings, barns and caves. Sony VPCEH2J1E battery

Behavior

Most owls are nocturnal, actively hunting their prey only in water and darkness. Several types of owl, however, are crepuscular—active during the twilight hours of dawn and dusk; one example is the Pygmy owl (Glaucidium). A few owls are active during the day also; examples are the Burrowing Owl (Speotyto cunicularia) and the Short-eared Owl (Asio flammeus)Sony VPCEH2H1E battery.

The serrations on the leading edge of an owl's flight feathers reduce noise

Owl eyes each have nictitating membranes that can move independently of each other, as seen on this Spotted Eagle-Owl in Johannesburg, South Africa

Owls yawn

Much of the owls' hunting strategy depends on stealth and surprise. Owls have at least two adaptations that aid them in achieving stealth. First, the dull coloration of their' feathers can render them almost invisible under certain conditionsSony VPCEH2F1E battery. Secondly, serrated edges on the leading edge of owls' remiges muffle an owl's wing beats, allowing an owl's flight to be practically silent. Some fish-eating owls, for which silence has no evolutionary advantage, lack this adaptation.

An owl's sharp beak and powerful talons allow it to kill its prey before swallowing it whole (if it is not too big). Scientists studying the diets of owls are helped by their habit of regurgitating the indigestible parts of their prey (such as bones, scales and fur) in the form of pelletsSony VPCEH2E0E battery. These "owl pellets" are plentiful and easy to interpret, and are often sold by companies to schools for dissection by students as a lesson in biology and ecology.

Adaptations for hunting

All owls are carnivorous birds of prey and live mainly on a diet of insects and small rodents such as mice, rats and hares. Some owls are also specifically adapted to hunt fish. They are very adept in hunting in their respective environments. Since owls can be found in nearly all parts of the world and across a multitude of ecosystemsSony VPCEH2D0E battery, their hunting skills and characteristics vary slightly from species to species, though most characteristics are shared among all species.

Flight and feathers

Most owls share an innate ability to fly almost silently and also more slowly in comparison to other birds of prey. Most owls live a mainly nocturnal lifestyle and being able to fly without making any noise gives them a strong advantage over their prey that are listening for any sign of noise in the dark nightSony VPCEH2C0E battery. A silent, slow flight is not as necessary for diurnal and crepuscular owls given that prey can usually see an owl approaching. While the morphological and biological mechanisms of this silent flight are more or less unknown, the structure of the feather has been heavily studied and accredited to a large portion of why they have this ability. Owls’ feathers are generally larger than the average birds’ feathersSony VPCEH1Z1E battery, have fewer radiates, longer pennulum, and achieve smooth edges with different rachis structures.[12] Serrated edges along the owl’s remiges bring the flapping of the wing down to a nearly silent mechanism. Research has shown that the serrations are more likely reducing aerodynamic disturbances, rather than simply reducing noise.[12] The surface of the flight feathers are covered with a velvety structure which absorbs the sound of the wing movingSony VPCEH1S9E battery. These unique structures reduce noise frequencies above 2 kHz,[13] making the sound level emitted drop below the typical hearing spectrum of the owl’s usual prey.[13][14] and also within the owl’s own best hearing range [4,5]. This optimizes the owl’s ability to silently fly in order to capture prey without the prey hearing the owl first as it flies in. It also allows the owl to monitor the sound output from its flight patternSony VPCEH1S8E battery.

Vision

Another characteristic of the owl which aids in their nocturnal prey capture is their eyesight. Owls are part of a small group of birds that live nocturnally, but do not use echolocation to guide them in flight in low-light situations. Owls are known for their disproportionally large eyes in comparison to their skullSony VPCEH1S1E battery. An apparent consequence of the evolution of an absolutely large eye in a relatively small skull is that the eye of the owl has become tubular in shape.[15] This shape is found in other so-called nocturnal eyes, such as the eyes of prosimians and bathypelagic fishes.[16] Since the eyes are fixed into these sclerotic tubes, they are unable to move the eyes in any direction.[17] Instead of moving their eyes, owls swivel their head to visualize their surroundingsSony VPCEH1S0E battery. The swiveling radius of the owl’s head is around 270˚, easily enabling them to see behind them without relocating the torso.[17] This ability keeps bodily movement at a minimum and thus reduces the amount of sound the owl makes as it waits for its prey. Owls are regarded as having the most frontally placed eyes amongst all avian groups, which gives them some of the largest binocular fields of visionSony VPCEH1M9E battery. But owls are farsighted and cannot focus on objects within a few centimeters of their eyes.[16][18] While it is commonly believed that owls have such great nocturnal vision due to their large (and thus very light-gathering) eyes and pupils and/or extremely sensitive rod receptors, the true cause for their ability to see in the night is due to neural mechanisms which mediate the extraction of spatial information gathered from the retinal image throughout the nocturnal luminance rangeSony VPCEH1M1E battery. These mechanisms are only able to function due to the large sized retinal image.[19] Thus, the primary nocturnal function in the vision of the owl is due to its large posterior nodal distance; retinal image brightness is only maximized to the owl within secondary neural functions.[19] These attributes of the owl cause the nocturnal eyesight to be far superior to that of its average prey. Sony VPCEH1L9E battery

Hearing

Owls exhibit specialized hearing functions and ear shapes that also aid in hunting. They are noted for asymmetrical ear placements on the skull in some genera. Owls can have either internal or external ears, but those genera exhibiting asymmetrical ear geometry only have external ear placements. Asymmetry has not been reported to extend to the middle or internal ear of the owlSony VPCEH1L8E battery. Asymmetrical ear placement on the skull allows the owl to pinpoint the location of its prey. This is especially true for strictly nocturnal species such as the barn owls 'Tyto' or Tengmalm’s Owl.[17] With ears set at different places on its skull, an owl is able to determine the direction from which the sound is coming by the minute difference in time that it takes for the sound waves to penetrate the left and right ears. Sony VPCEH1L0E batteryThe owl turns its head until the sound reaches both ears simultaneously, at which point it is directly facing the source of the sound. This time difference between ears is a matter of about 0.00003 seconds, or 30 millionths of a second. In coordination with this left to right calibration, some owls (like the barn owl) have slight up and down asymmetricality of the ears, which allows the owl to recognize whether a sound originates higher or lower in vertical space by the volume of the sound in each earSony VPCEH1J8E battery. If the sound is louder in the ear facing upwards, then the prey is higher up than the owl’s focus.[20] Like the eyes, which utilize feather movements to focus light, the ears are surrounded by feathers to maximize hearing capabilities. Behind the ear openings there are modified, dense feathers, densely packed to form a facial ruff, which creates an anteriorly-facing concave wall that cups the sound into the ear structure. Sony VPCEH1J1E batteryThis facial ruff is poorly defined in some species and prominent, nearly encircling the face, in other species. The facial disk also acts to direct sound into the ears, and a downward-facing, sharply triangular beak minimizes sound reflection away from the face. The shape of the facial disk is adjustable at will to focus sounds more effectively.[17] Owls have an audible range similar to that of humansSony VPCEH1E1E battery, but far more acute in certain frequencies, allowing them to detect even the slightest movements of their prey. Once an owl has determined the location of its prey, it flies towards it according to the last sound perceived. If the prey moves, the owl is able to adjust its flight pattern mid-flight.[20]

Talons

While the auditory and visual capabilities of the owl allow it to locate and pursue its prey, the talons and beak of the owl do the final workSony VPCEH1AJ battery. The owl kills its prey by using these talons to crush the skull and knead the body.[17] The crushing power of an owl’s talons varies according to prey size and type, and by the size of the owl. The Burrowing Owl (Athene cunicularia), a small partly insectivorous owl, has a release pressure of only 500 grams. The larger Barn Owl (Tyto alba) needs pressure of 3000 grams to release its preySony VPCCA1S1E/W battery, and one of the largest owls, the Great Horned Owl (Bubo virginianus) needs pressure of over 13,000 grams to release prey in its talons.[22] An owl’s talons, like those of most birds of prey, can seem massive in comparison to the body size outside of flight. The Masked owl has some of the proportionally longest talons of any bird of prey; they appear enormous in comparison to the body when fully extended to grasp prey. Sony VPCCA1S1E/P battery Owls' foot design differs from that of diurnal birds of prey because owls have a zygodactyl toe arrangement, with two toes directed forward and two toes directed backward during perching. During flight, the outer front toe swivels forward on a flexible joint so that three of the four toes are facing forward. Some owls’ talons have adapted to include filoplume feathers that aid in sensing the prey once it is close or has in fact made contact with the talonSony VPCCA1S1E/G battery, which is useful in capturing small prey at night. The underside of the talon foot is covered in a rough, knobby surface, which allows the owl to grasp its prey and hold it without having to keep the muscles tightly contracted.[20] An owl’s claws are sharp and curved. The family Tytonidae have inner and central toes of about equal length, while the family Strigidae have an inner toe that is distinctly shorter than the central one. Sony VPCCA1S1E/D batteryThese different morphologies allow efficiency in capturing prey specific to the different environments they inhabit.

Beak

The beak of the owl is short, curved and downward-facing, and typically hooked at the tip for gripping and tearing its prey. Once prey is captured, the scissor motion of the top and lower bill is used to tear the tissue and kill. The sharp lower edge of the upper bill works in coordination with the sharp upper edge of the lower bill to deliver this motion. Sony VPCCA1S1E/B batteryThe downward-facing beak allows the owl’s field of vision to be clear, as well as to direct sound into the ears without deflecting sound waves away from the face.

Snowy Owl blends well with its snowy surroundings

Camouflage

The coloration of the owl’s plumage plays a key role in its ability to sit still and blend into the environment, making it nearly invisible to prey. Owls tend to mimic the colorations and sometimes even the texture patterns of their surroundings, the common barn owl being an exception. Nyctea scandiacaSony VPCCA1S1E battery, or the Snowy Owl, appears nearly bleach-white in color with a few flecks of black, mimicking their snowy surroundings perfectly. Likewise, the Muted Wood-Owl (Strix ocellata) displays shades of brown, tan and black, making the owl nearly invisible in the surrounding trees, especially from behind. Usually, the only tell-tale sign of a perched owl will be its vocalizations or its vividly colored eyesSony VPCCA1C5E battery.

Evolution and systematics

Great Horned Owl (Bubo virginianus) sleeping during daytime in a hollow tree

The systematic placement of owls is disputed. For example, the Sibley-Ahlquist taxonomy finds that, based on DNA-DNA hybridization, owls are more closely related to the nightjars and their allies (Caprimulgiformes) than to the diurnal predators in the order Falconiformes; consequently, the Caprimulgiformes are placed in the StrigiformesSony VPCCA1AHJ battery, and the owls in general become a family Strigidae. A recent study indicates that the drastic rearrangement of the genome of the accipitrids may have obscured any close relationship of theirs with groups such as the owls.[24] In any case, the relationships of the Caprimulgiformes, the owls, the falcons and the accipitrid raptors are not resolved to satisfactionSony VPCCA1AGJ battery; currently there is an increasing trend to consider each group (with the possible exception of the accipitrids) a distinct order.

There are some 220 to 225 extant species of owls, subdivided into two families: typical owls (Strigidae) and barn-owls (Tytonidae). Some entirely extinct families have also been erected based on fossil remains; these differ much from modern owls in being less specialized or specialized in a very different way (such as the terrestrial Sophiornithidae) Sony VPCCA1AFJ battery. The Paleocene genera Berruornis and Ogygoptynx show that owls were already present as a distinct lineage some 60–57 mya (million years ago), and, hence, possibly also some 5 million years earlier, at the extinction of the non-avian dinosaurs. This makes them one of the oldest known groups of non-Galloanserae landbirds. The supposed "Cretaceous owls" Bradycneme and Heptasteornis are apparently non-avialan maniraptors. Sony VPCCA190 battery

During the Paleogene, the Strigiformes radiated into ecological niches now mostly filled by other groups of birds.[clarification needed] The owls as we know them today, on the other hand, evolved their characteristic morphology and adaptations during that time, too. By the early Neogene, the other lineages had been displaced by other bird ordersSony VPCCA18EC battery, leaving only barn-owls and typical owls. The latter at that time were usually a fairly generic type of (probably earless) owl similar to today's North American Spotted Owl or the European Tawny Owl; the diversity in size and ecology found in typical owls today developed only subsequently.

Around the Paleogene-Neogene boundary (some 25 mya) Sony VAIO VPCF135Z1E/B battery, barn-owls were the dominant group of owls in southern Europe and adjacent Asia at least; the distribution of fossil and present-day owl lineages indicates that their decline is contemporary with the evolution of the different major lineages of typical owls, which for the most part seems to have taken place in Eurasia. In the Americas, there was rather an expansion of immigrant lineages of ancestral typical owlsSony VAIO VPCF137HG/BI battery.

The supposed fossil herons "Ardea" perplexa (Middle Miocene of Sansan, France) and "Ardea" lignitum (Late Pliocene of Germany) were more probably owls; the latter was apparently close to the modern genus Bubo. Judging from this, the Late Miocene remains from France described as "Ardea" aureliensis should also be restudied.[26] The Messelasturidae, some of which were initially believed to be basal StrigiformesSony VAIO VPCF136FG/BI battery, are now generally accepted to be diurnal birds of prey showing some convergent evolution towards owls. The taxa often united under Strigogyps[27] were formerly placed in part with the owls, specifically the Sophiornithidae; they appear to be Ameghinornithidae instead.

For fossil species and paleosubspecies of extant taxa, see the genus and species articles.

Long-eared Owl (Asio otus) in erect pose

Unresolved and basal forms (all fossil)

Berruornis (Late Paleocene of France) basal? SophornithidaeSony VAIO VPCF135FG/B battery?

Strigiformes gen. et ap. indet. (Late Paleocene of Zhylga, Kazakhstan)

Palaeoglaux (Middle – Late Eocene of WC Europe) own family Palaeoglaucidae or Strigidae?

Palaeobyas (Late Eocene/Early Oligocene of Quercy, France) Tytonidae? Sophiornithidae?

Palaeotyto (Late Eocene/Early Oligocene of Quercy, France) Tytonidae? Sophiornithidae?

Strigiformes gen. et spp. indet. (Early Oligocene of Wyoming, USA)[29]

OgygoptyngidaeSony VAIO VPCF127HG/BI battery

Ogygoptynx (Middle/Late Paleocene of Colorado, USA)

Among the Kikuyu of Kenya it was believed that owls were harbingers of death. If one saw an owl or heard its hoot, someone was going to die. In general, owls are viewed as harbingers of bad luck, ill health, or death. The belief is widespread even today.[31]

The Little Owl, 1506, by Albrecht Dürer

The Americas

In the culture of the Uto-Aztec tribe, the Hopi, taboos surround owls, which are associated with sorcery and other evilsSony VAIO VPCF11Z1E battery. The Aztecs and Maya, along with other Natives of Mesoamerica, considered the owl a symbol of death and destruction. In fact, the Aztec god of death, Mictlantecuhtli, was often depicted with owls. There is an old saying in Mexico that is still in use[32]: Cuando el tecolote canta, el indio muere ("When the owl cries/sings, the Indian dies"). The Popol VuhSony VAIO VPCF11S1E battery, a Mayan religious text, describes owls as messengers of Xibalba (the Mayan "Place of Fright").[33] The belief that owls are messengers and harbingers of the dark powers is also found among the Hočągara (Winnebago) of Wisconsin.[34] When in earlier days the Hočągara committed the sin of killing enemies while they were within the sanctuary of the chief's lodge, an owl appeared and spoke to them in the voice of a humanSony VAIO VPCF11M1E/H battery, saying, "From now on the Hočągara will have no luck." This marked the beginning of the decline of their tribe.[35] An owl appeared to Glory of the Morning, the only female chief of the Hočąk nation, and uttered her name. Soon afterwards she died.[36] People often allude to the reputation of owls as bearers of supernatural danger when they tell misbehaving children, "the owls will get you." Sony VAIO VPCF11M1E battery Also, in the native Cherokee culture, as well as many other Native American cultures, owls are a very bad omen. It is said that if you are outside in the broad day light and an owl flies over your head a family member or loved one would die within the coming week.

Middle East

In Arab mythology, owls are seen as bad omens.[38]

Hinduism

Lakshmi with the owl

In Hinduism, an owl is the vahana, mount, of Goddess Lakshmi.

Western culture

The modern West generally associates owls with wisdom. This link goes back at least as far as Ancient Greece, where Athens, noted for art and scholarship, and Athena, Athens' patron goddess and the goddess of wisdom, had the owl as a symbol. Sony VAIO VPCF11JFX/B battery Marija Gimbutas traces veneration of the owl as a goddess, among other birds, to the culture of Old Europe, long pre-dating Indo-European cultures.[40]

T. F. Thiselton-Dyer in his Folk-lore of Shakespeare says that "from the earliest period it has been considered a bird of ill-omen, and Pliny tells us how, on one occasion, even Rome itself underwent a lustration, because one of them strayed into the Capitol. He represents it also as a funereal bird, Sony VAIO VPCF119FJ battery a monster of the night, the very abomination of human kind. Virgil describes its death-howl from the top of the temple by night, a circumstance introduced as a precursor of Dido's death. Ovid, too, constantly speaks of this bird's presence as an evil omen; and indeed the same notions respecting it may be found among the writings of most of the ancient poets." [41] A list of "omens drear" in John Keats' Hyperion includes the "gloom-bird's hated screech." Sony VAIO VPCF119FC/BI battery

In France, where owls are divided into eared owls (hiboux) and earless owls (chouettes), the former are seen as symbols of wisdom while the latter are assigned the grimmer meaning.

Three Canadian provinces have owls as provincial symbols: the Great Horned Owl in Alberta, the Great Grey Owl in Manitoba, and the Snowy Owl in QuebecSony VAIO VPCF119FC battery.

Use as rodent control

Encouraging natural predators to control rodent population is a natural form of pest control, along with excluding food sources for rodents. Placing a new box for owls on a property can help control rodent populations (one family of hungry barn owls can consume more than 3,000 rodents in a nesting season) while maintaining the naturally balanced food chain. Sony VAIO VPCF117HG/BI battery

Owl conservation issues

Laughing Owl (Sceloglaux albifacies), last seen in 1914

All owls are listed in Appendix II of the international CITES treaty (the Convention on Illegal Trade in Endangered Species of Wild Fauna and Flora). Although owls have long been hunted, a 2008 news story from Malaysia indicates that the magnitude of owl poaching may be on the rise. In November 2008, TRAFFIC reported the seizure of 900 plucked and "oven-ready" owls in Peninsular MalaysiaSony VAIO VPCF116FG/BI battery. Said Chris Shepherd, Senior Programme Officer for TRAFFIC's Southeast Asia office, "This is the first time we know of where 'ready-prepared' owls have been seized in Malaysia, and it may mark the start of a new trend in wild meat from the region. We will be monitoring developments closely." Traffic commended the Department of Wildlife and National Parks in Malaysia for the raid that exposed the huge haul of owls. Included in the seizure were dead and plucked Barn OwlsSony VAIO VPCF115FG/B battery, Spotted Wood Owls, Crested Serpent Eagles, Barred Eagles, and Brown Wood Owls, as well as 7,000 live lizards.

Lincoln Park is a 1,208 acre (4.9 km², 1.8875 mi², 488,86 ha) park along the lakefront of Chicago, Illinois' North Side, facing Lake Michigan. Lincoln Park is Chicago's largest public park. The park, named after Abraham Lincoln, stretches for seven miles (11 km) from Ohio Street (400 N) on the south to near Ardmore Avenue (5800 N) on the north, just north of the Lake Shore Drive terminus at Hollywood Avenue. Sony VAIO PCG-8131M batterySeveral museums are located between North Avenue (1600 N) and Diversey Parkway (2800 N) in the neighborhood that takes its name from the park, Lincoln Park. The park further to the north is characterized by parkland, beaches, recreational areas, nature reserves, and harbors. To the south, there is a more narrow strip of beaches east of Lake Shore Drive, almost to downtown. Lincoln Park, with 20 million visitors a year, is the second most visited park in the United States. Sony VAIO PCG-8152M battery

The park's recreational facilities include 15 baseball areas, 6 basketball courts, softball fields, soccer fields, 35 tennis courts, 163 volley ball courts, field houses, a target archery field, a driving range and golf course. The park also includes a number of harbours with boating facilities, as well as public beaches. There are landscaped gardens, public art, bird refuges, a zooSony VAIO PCG-31311M battery, the Lincoln Park Conservatory, the Chicago History Museum, the Peggy Notebaert Nature Museum, the Alfred Caldwell Lily Pool, and a theater on the lake with regular outdoor performances during the summer.

History

A concert in Lincoln Park circa 1907.

In 1860, Lake Park (also called Cemetery Park), the precursor of today's park, was established by the city on the lands just to the north of the city's burial ground. Five years later, on June 12, 1865, the park was renamed to honor the recently assassinated President Abraham LincolnSony VAIO PCG-31111M battery.

Added to the National Register of Historic Places in 1994,[6] part of the oldest section of today's Lincoln Park near North Avenue began its existence as the City Cemetery in 1843. This was subdivided into a Potter's Field, Catholic cemetery, Jewish cemetery, and the general City Cemetery. These cemeteries were the only cemeteries in the Chicago area until 1859Sony VAIO PCG-8112M battery. In 1852, David Kennison, who is said to have been born in 1736, died and was buried in City Cemetery. Another notable burial in the cemetery was Chicago Mayor James Curtiss, whose body was lost when the cemetery was added to the park.

Photochrom of the Grant Memorial ca. 1901

Throughout the late 1850s, there was discussion of closing the cemetery or abandoning it because of health concerns. In the fall of 1858, Dr. John H. Rauch MD suggested that the burial grounds were a health risk, which "might serve extremely well for plantations of grove and forest trees" that would be "useful and ornamental to the city." Sony VAIO PCG-7186M battery The idea was dropped during the Civil War, but revived by Dr. Rauch after the war ended. [8] By 1864, the city council had decided to add all the 120-acre (0.49 km2) cemetery lands north of North Avenue to the park by relocating the graves. The cemetery sections south of North Avenue were also relocated but this land was left for residential development. To this day, the Couch mausoleum can still be seen as the most visible reminder of the history as a cemeterySony VAIO PCG-7171M battery, standing amidst trees, behind the Chicago History Museum. Ira Couch, who is interred in the tomb, was one of Chicago's earliest innkeepers, opening the Tremont House in 1835. Couch is believed to not be the only person interred in the old burial ground in Lincoln Park. A plaque placed nearby states that "the remains of six Couch family members and one family friend are in the tomb." [9]Partially due to the destruction of the Chicago Fire on tombstonesSony VAIO PCG-9Z1M battery, it was difficult to remove many of the remains. As recently as 1998, construction in the park has revealed more bodies left over from the nineteenth century.[10]

Another large and notable group of graves relocated from the site of today's Lincoln Park were those of approximately 4,000 Confederate prisoners of war who died at Camp Douglas. Many prisoners perished between 1862 and 1865 as a result of the poor condition they were in when taken on the battlefield, or of disease and privation existing at the Federal prisonSony VAIO PCG-5S1M battery. Although the camp was located south of downtown Chicago, near the stockyards, the remains were originally interred at the site of today's Lincoln Park. Today, their gravesites may be found at Oak Woods Cemetery in the southern part of Chicago. A one acre (4,000 m²) mass grave and a monument erected by Southerners and Chicago friends in 1895 memorializes these Southerners whose earthly remnants remain in the NorthSony VAIO PCG-5P1M battery. Author George Levy believes that remains of many of the confederate prisoners are still to be found beneath what are currently baseball fields, the former site of the potter's field.[11]

From the 1860s through the 1950s the park expanded South and then North along seven miles (11 km) of Chicago's Lakefront. (See reference notes 1, 2 and 3). The establishment of public parkland along all of Chicago's lakefront was a central tennet of the 1909 Burnham Plan for the development of ChicagoSony VAIO PCG-5N2M battery.

Another aspect of park history were the Young Lords Lincoln Park neighborhood sit ins and take-overs of institutions under the leadership of Jose Cha Cha Jimenez, protesting the displacement of Latinos by Mayor Richard J. Daley's urban renewal policies. It was also the scene of violent events that took place during the 1968 Democratic National Convention. These events transpired around the convention center, Grant ParkSony VAIO PCG-3C2M battery, Old Town, and the park adjacent (on Clark Street) called Lincoln Park.

“I pointed out that it was in the best interests of the City to have us in Lincoln Park ten miles (16 km) away from the Convention hall. I said we had no intention of marching on the Convention hall, that I didn't particularly think that politics in America could be changed by marches and rallies, that what we were presenting was an alternative life style, and we hoped that people of Chicago would come up, and mingle in Lincoln Park and see what we were aboutSony VAIO PCG-8161M battery.    ”

— Abbie Hoffman, from the Chicago 7 trial

Zoo, Conservatory, and museums

Lincoln Park Zoo Nature Boardwalk

Lincoln Park Conservatory

Alfred Caldwell Lily Pool in Lincoln Park is a National Historic Landmark listing.

Peggy Notabeart Nature Museum-Chicago Academy of Sciences, south wing with tallgrass prairie overlook

Zoo

Main article: Lincoln Park Zoo

41.921375°N 87.633841°W

Lincoln Park is well known for the Lincoln Park Zoo, a free zoo that is open year-round.[12] Lincoln Park Zoo is home to a wide variety of animals. The zoo includes big cats, polar bears, penguins, gorillas, reptiles, monkeys, and other species totalling nearly 1,250 animalsSony VAIO PCG-8141M battery. Two sections of Lincoln Park Zoo have been set aside for children. The partially indoor Pritzker Family Children's Zoo includes habitats of various North American wildlife, and the Farm-in-the-Zoo Presented by John Deere is a working reproduction of a Midwestern farm containing horses and livestock such as pigs, cows, and sheep. At the Farm-in-the-Zoo, children can feed and interact with the animals and view live demonstrations of farm work such as the milking of cowsSony VAIO PCG-3J1M battery. In 2010, the Zoo transformed the South Pond, to create a wildlife marsh habitat, with a Nature Boardwalk.

Conservatory

Main article: Lincoln Park Conservatory

The Lincoln Park Conservatory offers year round displays of plants from many different climates around the world.[13] Today's conservatory was built in stages from 1890 to 1895. It consists of a vestibule, four display halls and fifteen propagating and growing houses. The vestibule and Palm House were built and opened to the public in 1892 and contain giant palms and rubber treesSony VAIO PCG-3H1M battery, including a 15 m (50 ft) fiddle-leaf rubber tree planted in 1891. In the Palm House, one can also find Garden Figure, a sculpture by Frederick Hibbard. The Fern Room or Fernery was opened in 1895. It contains plants of the forest floor, primarily a vast collection of ferns. The Tropical Room was originally called the stove house. Opened in 1895, it contained an assortment of tropical plants suspended from bark-covered wallsSony VAIO PCG-3F1M battery. It is now called the Orchid Room and has a collection of approximately 25,000 natural species. The Display House is used for seasonal flower and plant exhibits. A docent program run by the Chicago Park District and Lincoln Park Conservancy, provides free tours of the Conservatory and its outdoor gardens from 1-4 p.m. on Fridays, Saturdays, and Sundays and from 9 to Noon on Saturdays
Sony VAIO PCG-3C1M battery.

Lily Pool

Main article: Alfred Caldwell Lily Pool

Located on Fullerton Parkway between Stockton and Cannon Drives, the Alfred Caldwell Lily Pool is an historic example of Prairie School landscape architecture. The Lily Pool was listed on the National Register of Historic Places and as a National Historic Landmark on February 17, 2006.[14] The Lily Pool had originally been built to cultivate tropical water lilies in 1889. Sony VAIO PCG-9Z2L battery In the 1930s, landscape architect Alfred Caldwell was hired by the Works Progress Administration to redesign the pool in the Prairie School style.[16] From 1998 to 2002, the Lily Pool underwent an extensive restoration by the Lincoln Park Conservancy and Chicago Park District, which earned the site its historic designations, and renamed the site after Alfred Caldwell. The Lily Pool is open seasonally from mid-April to mid-November from 7:30 a.m. to the earlier of dusk or 7:30 p.m. every daySony VAIO PCG-9Z1L battery. A docent program run by the Chicago Park District and Lincoln Park Conservancy offers free tours from 1-4 p.m. on Fridays, Saturdays, and Sundays, and from 9 - Noon on Saturdays during operating season.

Nature Museum

Main article: Peggy Notebaert Nature Museum

First established in 1857 as the Chicago Academy of Sciences and now occupying its new facility in 1999 as the Nature Museum, it descends from the Park District's first museum in the parks. The museum's exhibits include displays about the ecological history of the Illinois regionSony VAIO PCG-9131L battery, a live butterfly house, and a green home demonstration.[17] The butterfly house features more than 200 species of exotic butterflies. The museum also offers educational programs for adults and children.[18]

History Museum

Main article: Chicago History Museum

Located at Clark Street and North Avenue, the Chicago History Museum is dedicated to everything about Chicago's human history. Perhaps among its most well-known possessions are Abraham Lincoln's deathbed and several furniture pieces from the room where he died in the Petersen HouseSony VAIO PCG-8161L battery, as well as clothing he and wife Mary Todd Lincoln wore the evening of his assassination.[19][20] The museum also houses Chicago's most important collection of materials related to local history. In addition to the exhibits, the museum continues to house an extensive research library which includes books and other published materials, manuscripts, paintings, sculptures and photosSony VAIO PCG-8152L battery.

Recreational areas

Children playing in Lincoln Park in winter snowstorm

Montrose Harbor and other harbors provide marina and docking facilities

First tee at Waveland Golf Course

Facilities

Lincoln Park runs through five Chicago neighborhoods: from north to south, they are Edgewater, Uptown, Lake View, Lincoln Park and Near North. Along its seven mile (11 km) streach, Lincoln Park has many specialized spaces for recreational activities. The Park contains playgrounds, tennis and basketball courts, boating facilities, beaches, field and beach housesSony VAIO PCG-8141L battery, running and bike paths, playing fields and pitches for football, rugby, baseball, softball, cricket, soccer, volleyball, archery, a golf course, driving range, and areas for horseback riding.

Beaches

Main article: Chicago beaches#Lincoln Park Beaches

There are seven public beaches for swimming, sunbathing and beach volleyball along the Park's 7 mile shoreline that are guarded during the summer months. The beaches from north to south are, Thorndale, Hollywood, and Foster in Edgewater; Montrose in Uptown; North Avenue in Lincoln Park; and Oak Street and Ohio in Near North. The first City of Chicago public beach, North Avenue Beach, opened in Lincoln Park in 1895. Sony VAIO PCG-8131L battery

Golf

The Waveland Avenue Golf Course (now, Sydney R Marovitz) in the Uptown and Lakeview, Chicago neighborhoods section of the park provides a lakside setting for the game.[22] (41°57′9″N 87°38′27.4″W) Known for its challenging narrow fairways, it offers nine tees on a par 36 course. Further south, inland of Lakeshore Drive, is a driving range and miniature golfcourseSony VAIO PCG-81312L battery.

Boating

There are three harbors in the Park providing marina and docking facilities for boaters: north to south, they are Montrose in Uptown, Lakeview's Belmont Harbor, and Diversey Harbor in the Lakeview and the Lincoln Park Neighborhoods .[23] Montrose Harbor provides 630 dock facilities and is home to the Chicago Corinthian Yacht Club. Sony VAIO PCG-81214L battery Belmont Harbor provides 730 moorings, a fuel dock and a ship store.[25] The Chicago Yacht Club has a Belmont station and the Belmont Yacht Club is located here. Diversey Harbor has 714 moorings and the Diversey Yacht Club provides a fueling dock.[26] There is also a public launch at Diversey. In addition, the park also has rowing, sculling, and crewing channelsSony VAIO PCG-81115L battery.

Chicago Lakefront Trail

The Chicago Lakefront Trail (abbreviated as LFT) is an 18-mile multi-use path in Chicago, Illinois along the coast of Lake Michigan. It is popular with cyclists and joggers. It is designed to promote bicycle commuting. From north to south, it runs through Lincoln Park, Grant Park, Burnham Park and Jackson ParkSony VAIO PCG-81114L battery.

Wildlife

North Pond

Green Heron at the North Pond Nature Sanctuary

The North Pond Nature Sanctuary (41°55′42.12″N 87°38′15.66″W), located between Fullerton, Diversey, Stockton and Cannon, is a ten-acre pond that has become an important wildlife area. Historically the site was a dune, then a dumping ground, and converted in 1999-2000 into a natural area with a littoral zone that greatly improved the water quality by re-establishing native Midwestern ecologySony VAIO PCG-81113L battery. The upland restoration of prairie, savanna, and woodland plants has included only top quality native species such as little bluestem, sky-blue aster, nodding wild onion, side-oats grama, butterfly weed, purple prairie clover, rough blazing star, wild quinine, prairie phlox, coneflowers, false dragonhead, northern prairie dropseed, showy goldenrod, rattlesnake masterSony VAIO PCG-7142L battery, shooting star, and wild bergamot.[28] The North Pond Nature Sanctuary is notable as the site where Mayor Richard M. Daley and the US Fish and Wildlife Service signed an Urban Conservation Treaty for Migratory Birds in April, 2004, making the city eligible for federal funds to restore habitat for the lakefront migratory pathway for birdsSony VAIO PCG-7141L battery.

Restoration with native plants has drawn a great diversity of wildlife to this urban pond including many species of birds, turtles, frogs, and even a few beavers. Great Blue Herons, Black-crowned Night Herons, Green Herons, Mallards, Wood Ducks, Song Sparrows and woodpeckers can regularly be spotted at the North Pond Nature SanctuarySony VAIO PCG-71111L battery.

Animal Sanctuaries

Lake dune and beach grass (left), and tallgrass prairie and woodland reserve (right), in Lincoln Park at Montrose Point, a former Nike missile base site turned nature reserve.

Further north in the park, in the Lake View neighborhood (3600 N), there is the Bill Jarvis Migratory Bird Sanctuary (41°56′54.64″N 87°38′26.47″W; formerly, Lincoln Park Addison Migratory Bird Sanctuary).[29] First constructed in the 1920sSony VAIO PCG-61411L battery, its spring is supplied with city water to mimic a natural lake marsh environment.[30] It is a unique reserve in that most of its 7-acre (28,000 m2) area is entirely fenced around to preserve the habitat from human encroachment. Instead, a nature trail and a viewing platform are at its surrounding perimeter. In 1968, the entire site was almost bulldozed for park development but its Lake View neighbors led a successful campaign to save and restore itSony VAIO PCG-61112L battery. Today it hosts more than 150 species of birds including, six species of herons, like the black crowned night heron; wood ducks; woodcock; hawks; yellow-billed cuckoos; hummingbirds; thrushes; vireos; 34 species of warblers; and 18 native species of sparrows. In addition, small mammals such as rabbit, opossum, raccoon, and occasionally fox and coyote make there home hereSony VAIO PCG-61111L battery.

In the Uptown neighborhood (4400 N;41°57′47.95″N 87°38′1.75″W), there is the 15-acre (61,000 m2) Montrose Point Bird Sanctuary (including “The Magic Hedge”).[31] Its history is perhaps unusual for a nature preserve. During the Cold War, Montrose point, which juts out into Lake Michigan, was used by the United States Army as a Nike missile base.[32] The Army camouflaged their missile launchers and barracks behind honeysuckle hedges.Sony VAIO PCG-5T4L battery When the Army left in the 1970s, bird watchers noticed how the honeysuckle attracted birds. They successfully lobbied the park district for a new preserve. Now, after extensive replanting, the site supports woodland, tall prairie, and lake dune habitat that annually attracts tens of thousands of migratory birds of more than 300 different speciesSony VAIO PCG-5T3L battery.

Public art

Looking North, Lincoln Park is all the green (and sand) areas in this picture, streaching to the horizon. Lake Shore Drive runs up the middle. The visible Lincoln Park beaches are Oak Street Beach (bottom right) and North Ave Beach (upper-middle right). The Zoo and original park are in the green area to the left of Lake Shore Drive (upper-middle left). Top center are more of Lincoln Park's green northern reachesSony VAIO PCG-5T2L battery, including Montrose Point juting out into the lake. Not visible are Ohio Street beach (to the south of this picture) and the beaches, harbors and parklands, beyond the northern horizon.

Lincoln Park is known for its statuary.[33] Walking through the park, one sees many of Chicago's great works of art. There is a famous statue of Abraham Lincoln in Lincoln Park by Augustus Saint-Gaudens, the same sculptor who created the Lincoln statue in Grant Park. Replicas of Lincoln Park's "Standing Lincoln" can be found at Lincoln's tombSony VAIO PCG-5S3L battery, Springfield and in Parliament Square, London. The statue is located at Dearborn and North Avenues. It was fully restored in 1989 by the Lincoln Park Conservancy's Adopt-A-Monument Program, and 8,200 s.f. of formal gardens were added in front of the monument.

The only other person who is immortalized by statues in both Grant and Lincoln Parks is Alexander Hamilton, the Lincoln Park statue is sculpted by John AngelSony VAIO PCG-5S2L battery. Just as there is an Abraham Lincoln statue in Grant Park, there is a massive memorial to Ulysses S. Grant in Lincoln Park overlooking Cannon Drive. The sculpture was created in 1891 by Louis Rebisso.

John Gelert's Hans Christian Andersen (1896) on Stockton Drive near Webster Avenue provides a tribute to the Danish storyteller. The Eugene Field Memorial (1922) designed by Edward McCartan remembers the Chicago Daily News columnist and poet who wrote "Little Boy Blue" and "Winken, Blinken, and Nod." Sony VAIO PCG-5S1L battery William Ordway Partridge's statue of William Shakespeare (1894) provides a third great story-teller in Lincoln Park. This seated Shakespeare provides a lap for children to climb onto. A bust of Sir Georg Solti, the former conductor of the Chicago Symphony Orchestra was also situated in the Lincoln Park Conservatory's formal garden until its relocation to Grant Park in October, 2006. Statues honoring the German poets Johann Wolfgang von Goethe and Friedrich Schiller can also be found in Lincoln parkSony VAIO PCG-5R2L battery. The large Goethe statue is located near Diversey and Stockton. The smaller Schiller statue is located near the western entrance to the zoo.

At Addison Street stands a 40-foot (12 m) totem pole depicting Kwanusila the Thunderbird. Finally, a statue of John Peter Altgeld (1915), the nineteenth-century Illinois Governor who pardoned the Haymarket Square rioters, can be seen just south of Diversey. This statue was created by Gutzon Borglum and unveiled on September 6, 1915Sony VAIO PCG-5R1L battery. Borglum went on to become the sculptor of the Mount Rushmore Monument.

Miami ( /maɪˈæmi/ or /maɪˈæmə/) is a city located on the Atlantic coast in southeastern Florida and the county seat of Miami-Dade County, the most populous county in Florida and the eighth-most populous county in the United States with a population of 2,500,625.[7] The 42nd largest city proper in the United States, with a population of 408,568, it is the principalSony VAIO PCG-5P4L battery, central, and most populous city of the South Florida metropolitan area, and the most populous metropolis in the Southeastern United States.[8] According to the US Census Bureau, Miami's metro area is the seventh most populous and fifth-largest urban area in the United States, with a population of around 5.5 million.

Miami is a major center and a leader in finance, commerce, culture, media, entertainment, the arts, and international tradeSony VAIO PCG-5P2L battery. In 2010, Miami was classified as a Alpha- World City in the World Cities Study Group’s inventory.[13] In 2010, Miami ranked seventh in the United States in terms of finance, commerce, culture, entertainment, fashion, education, and other sectors. It ranked thirty-third among global cities.[14] In 2008, Forbes magazine ranked Miami "America's Cleanest City", for its year-round good air qualitySony VAIO PCG-5N4L battery, vast green spaces, clean drinking water, clean streets and city-wide recycling programs.[15] According to a 2009 UBS study of 73 world cities, Miami was ranked as the richest city in the United States, and the world's fifth-richest city in terms of purchasing power.[16] Miami is nicknamed the "Capital of Latin America",[1] is the 2nd largest U.S. city (after El Paso) with a Spanish-speaking majority, and the largest city with a Cuban-American plurality. Sony VAIO PCG-5N2L battery

Downtown Miami and South Florida are home to the largest concentration of international banks in the United States, and is home to many large companies both nationally and internationally.[18][19] The Civic Center is a major center for hospitals, research institutes, medical centers, and biotechnology industriesSony VAIO PCG-51513L battery. For more than two decades, the Port of Miami, known as the "Cruise Capital of the World," has been the number one cruise passenger port in the world, accommodating some of the world's largest cruise ships and operations, and is currently the busiest in both passenger traffic and cruise lines.

History

Approximately 400 men voted for Miami's incorporation in 1896 in the building to the leftSony VAIO PCG-51511L battery.

The Downtown Miami Historic District is the city's largest historic district, with buildings ranging from 1896-1939 in the heart of Downtown

Main article: History of Miami

See also: National Register of Historic Places listings in Miami, Florida

The Miami area was first inhabited for more than one thousand years by the Tequestas, but was later claimed for Spain in 1566 by Pedro Menéndez de Avilés. A Spanish mission was constructed one year later in 1567. In 1836, Fort Dallas was built, and the Miami area subsequently became a site of fighting during the Second Seminole WarSony VAIO PCG-51412L battery.

Miami holds the distinction of being "the only major city in the United States conceived by a woman, Julia Tuttle,"[22] who was a local citrus grower and a wealthy Cleveland native. The Miami area was better known as "Biscayne Bay Country" in the early years of its growth. Some published reports described the area as a promising wilderness.[23] The area was also characterized as "one of the finest building sites in Florida." Sony VAIO PCG-51411L batteryThe Great Freeze of 1894–95 hastened Miami's growth, as the crops of the Miami area were the only ones in Florida that survived. Julia Tuttle subsequently convinced Henry Flagler, a railroad tycoon, to expand his Florida East Coast Railway to the region, for which she became known as "the mother of Miami."[25] Miami was officially incorporated as a city on July 28, 1896 with a population of just over 300. Sony VAIO PCG-51312L battery It was named for the nearby Miami River, itself named for the Mayaimi Indians who previously lived around Lake Okeechobee.[citation needed]

Miami prospered during the 1920s with an increase in population and infrastructure but weakened after the collapse of the Florida land boom of the 1920s, the 1926 Miami Hurricane and the Great Depression in the 1930s. When World War II began, Miami, well-situated due to its location on the southern coast of FloridaSony VAIO PCG-51311L battery, played an important role in the battle against German submarines. The war helped to expand Miami's population; by 1940, 172,172 people lived in the city. After Fidel Castro rose to power in 1959, many Cubans sought refuge in Miami, further increasing the population. In the 1980s and 1990s, various crises struck South Florida, among them the Arthur McDuffie beating and the subsequent riot, drug wars, Hurricane Andrew, and the Elián González uproar. NeverthelessSony VAIO PCG-51211L battery, in the latter half of the 20th century, Miami became a major international, financial, and cultural center.

Miami and its metropolitan area grew from just over one thousand residents to nearly five and a half million residents in just 110 years (1896–2006). The city's nickname, The Magic City, comes from this rapid growth. Winter visitors remarked that the city grew so much from one year to the next that it was like magic. Sony VAIO PCG-41112L battery

Geography

The mouth of the Miami River at Brickell Key.

The city proper is home to less than 1 in 13 residents of South Florida. Additionally, 52% of Miami-Dade County's population doesn't live in any incorporated city.

Miami and its suburbs are located on a broad plain between the Florida Everglades to the west and Biscayne Bay to the east that also extends from Florida Bay north to Lake Okeechobee. The elevation of the area never rises above 40 ft (12 m)[28] and averages at around 6 ft (1.8 m) Sony VAIO PCG-3A4L batteryabove mean sea level in most neighborhoods, especially near the coast. The highest undulations are found along the coastal Miami Rock Ridge, whose substrate underlies most of the eastern Miami metropolitan region. The main portion of the city lies on the shores of Biscayne Bay which contains several hundred natural and artificially created barrier islands, the largest of which contains Miami Beach and South Beach. The Gulf Stream, a warm ocean currentSony VAIO PCG-3A3L battery, runs northward just 15 miles (24 km) off the coast, allowing the city's climate to stay warm and mild all year.

Geology

View from one of the higher points in Miami, west of downtown. The highest natural point in Miami is in Coconut Grove, near the bay, along the Miami Rock Ridge at 24 feet (7.3 m) above sea level.[30]

The surface bedrock under the Miami area is called Miami oolite or Miami limestone. This bedrock is covered by a thin layer of soil, and is no more than 50 feet (15 m) thick. Miami limestone formed as the result of the drastic changes in sea level associated with recent glaciations or ice agesSony VAIO PCG-3A2L battery. Beginning some 130,000 years ago the Sangamonian Stage raised sea levels to approximately 25 feet (7.6 m) above the current level. All of southern Florida was covered by a shallow sea. Several parallel lines of reef formed along the edge of the submerged Florida plateau, stretching from the present Miami area to what is now the Dry Tortugas. The area behind this reef line was in effect a large lagoonSony VAIO PCG-3A1L battery, and the Miami limestone formed throughout the area from the deposition of oolites and the shells of bryozoans. Starting about 100,000 years ago the Wisconsin glaciation began lowering sea levels, exposing the floor of the lagoon. By 15,000 years ago, the sea level had dropped to 300 to 350 feet (110 m) below the contemporary level. The sea level rose quickly after that, stabilizing at the current level about 4000 years ago, leaving the mainland of South Florida just above sea levelSony VAIO PCG-394L battery.

Beneath the plain lies the Biscayne Aquifer,[31] a natural underground source of fresh water that extends from southern Palm Beach County to Florida Bay, with its highest point peaking around the cities of Miami Springs and Hialeah. Most of the South Florida metropolitan area obtains its drinking water from this aquifer. As a result of the aquifer, it is not possible to dig more than 15 to 20 ft Sony VAIO PCG-393L battery (4.6 to 6.1 m) beneath the city without hitting water, which impedes underground construction. For this reason, the mass transit systems in and around Miami are elevated or at-grade.

Most of the western fringes of the city extend into the Everglades, a subtropical marshland located in the southern portion of the U.S. state of Florida. This causes occasional problems with local wildlife such as alligators venturing into Miami communities and major highwaysSony VAIO PCG-391L battery.

In terms of land area, Miami is one of the smallest major cities in the United States. According to the US Census Bureau, the city encompasses a total area of 55.27 sq mi (143.1 km2). Of that area, 35.67 sq mi (92.4 km2) is land and 19.59 sq mi (50.7 km2) is water. That means Miami comprises over 400,000 people in a mere 35 square miles (91 km2), making it one of the most densely populated cities in the United StatesSony VAIO PCG-384L battery, along with New York City, San Francisco, and Chicago among others. Miami is located at 25°47′16″N 80°13′27″W.

Climate

Main article: Climate of Miami

Typical summer afternoon thunderstorm rolling in from the Everglades.

Miami has a tropical monsoon climate (Köppen climate classification Am)[33] with hot and humid summers and short, warm winters, with a marked drier season in the winter. Its sea-level elevation, coastal location, position just above the Tropic of Cancer, and proximity to the Gulf Stream shapes its climate. With January averaging 67.2 °F (19.6 °C)Sony VAIO PCG-383L battery, winter features mild to warm temperatures; cool air usually settles after the passage of a cold front, which produces much of the little amount of rainfall. Lows sometimes fall below 50 °F (10 °C), but very rarely below 35 °F (2 °C). Highs generally range between 70–77 °F (21–25 °C). The wet season begins some time in May, ending in mid-October. During this period, temperatures are in the mid 80s to low 90s (29–35 °C) Sony VAIO PCG-382L battery, accompanied by high humidity, though the heat is often relieved by afternoon thunderstorms or a sea breeze that develops off the Atlantic Ocean, which then allow lower temperatures, but conditions still remain very muggy. Much of the year's 55.9 inches (1,420 mm) of rainfall occurs during this period.

Extremes range from 27 °F (−2.8 °C) on February 3, 1917 to 100 °F (38 °C) on July 21, 1940.[34] Miami has never recorded an accumulation of snow, and has only once recorded snow flurries, on January 19, 1977Sony VAIO PCG-381L battery.

Hurricane season officially runs from June 1 through November 30, although hurricanes can develop beyond those dates. The most likely time for Miami to be hit is during the peak of the Cape Verde season which is mid-August through the end of September.[36] Although tornadoes are uncommon in the Miami area, a tornado struck the city in 1925 and again in 1997Sony VAIO PCG-7185L battery.

Neighborhoods

Miami is partitioned into many different sections, roughly into North, South, West and Downtown. The heart of the city is Downtown Miami and is technically on the eastern side of the city. This area includes Brickell, Virginia Key, Watson Island, and the Port of Miami. Downtown is South Florida's central business district, and Florida's largest and most influential central business districtSony VAIO PCG-7184L battery. Downtown has the largest concentration of international banks in the U.S. along Brickell Avenue. Downtown is home to many major banks, courthouses, financial headquarters, cultural and tourist attractions, schools, parks and a large residential population. East of Downtown, across Biscayne Bay is South Beach. Just northwest of Downtown, is the Civic Center, which is Miami's center for hospitalsSony VAIO PCG-7183L battery, research institutes and biotechnology with hospitals such as Jackson Memorial Hospital, Miami VA Hospital, and the University of Miami's Leonard M. Miller School of Medicine.

The southern side of Miami includes Coral Way, The Roads and Coconut Grove. Coral Way is a historic residential neighborhood built in 1922 connecting Downtown with Coral Gables, and is home to many old homes and tree-lined streetsSony VAIO PCG-7182L battery. Coconut Grove was established in 1825 and is the location of Miami's City Hall in Dinner Key, the Coconut Grove Playhouse, CocoWalk, many nightclubs, bars, restaurants and bohemian shops, and as such, is very popular with local college students. It is a historic neighborhood with narrow, winding roads, and a heavy tree canopy. Coconut Grove has many parks and gardens such as Villa VizcayaSony VAIO PCG-7181L battery, The Kampong, The Barnacle Historic State Park, and is the home of the Coconut Grove Convention Center, as well as many of the country's most prestigious private schools, and numerous historic homes and estates.

The western side of Miami includes Little Havana, West Flagler, and Flagami, and is home to many of the city's traditionally immigrant neighborhoods. Although at one time a mostly Jewish neighborhoodSony VAIO PCG-7174L battery, today western Miami is home to immigrants from mostly Central America and Cuba, while the west central neighborhood of Allapattah is a multicultural community of many ethnicities.

The northern side of Miami includes Midtown, a district with a great mix of diversity with many West Indians, Hispanics, European Americans, bohemians, and artists. Edgewater, and Wynwood, are neighborhoods of Midtown and are made up mostly of high-rise residential towers and are home to the Adrienne Arsht Center for the Performing ArtsSony VAIO PCG-7173L battery. The wealthier residents usually live in the northeastern part, in Midtown, the Design District, and the Upper East Side, with many sought after 1920s homes and home of the MiMo Historic District, a style of architecture originated in Miami in the 1950s. The northern side of Miami, also has notable African American and Caribbean immigrant communities such as Little Haiti, Overtown (home of the Lyric Theater), and Liberty CitySony VAIO PCG-7172L battery.

Culture

Entertainment and performing arts

Adrienne Arsht Center for the Performing Arts, the second-largest performing arts center in the United States.

Miami is home to many entertainment venues, theaters, museums, parks and performing arts centers. The newest addition to the Miami arts scene is the Adrienne Arsht Center for the Performing Arts, the second-largest performing arts center in the United States after the Lincoln Center in New York CitySony VAIO PCG-7171L battery, and is the home of the Florida Grand Opera. Within it are the Ziff Ballet Opera House, the center's largest venue, the Knight Concert Hall, the Carnival Studio Theater and the Peacock Rehearsal Studio. The center attracts many large scale operas, ballets, concerts, and musicals from around the world and is Florida's grandest performing arts center. Other performing arts venues in Miami include the Gusman Center for the Performing ArtsSony VAIO PCG-7162L battery, Coconut Grove Playhouse, Colony Theatre, Lincoln Theatre, New World Center, Actor's Playhouse at the Miracle Theatre, Jackie Gleason Theatre, Manuel Artime Theater, Ring Theatre, Playground Theatre, Wertheim Performing Arts Center, the Fair Expo Center and the Bayfront Park Amphitheater for outdoor music events.

The city attracts a large number of musicians, singers, actors, dancers, and orchestral players. Miami has numerous orchestrasSony VAIO PCG-7161L battery, symphonies and performing art conservatories. Some of these include the Florida Grand Opera, Frost School of Music, Miami City Ballet, Miami Conservatory, Miami Wind Symphony, New World School of the Arts, New World Symphony Orchestra, as well as the music, theater and art schools of the city's many universities and schoolsSony VAIO PCG-7154L battery.

Miami is also a major fashion center, home to models and some of the top modeling agencies in the world. Miami is also host to many fashion shows and events, including the annual Miami Fashion Week and the Mercedes-Benz Fashion Week Miami held in the Wynwood Art District. Sony VAIO PCG-7153L battery

Museums and art

The city is home to numerous museums as well, many of which are in Downtown. These include the Bass Museum, Coral Gables Museum, Frost Art Museum, Historical Museum of Southern Florida, Jewish Museum of Florida, Lowe Art Museum, Miami Art Museum, Miami Children's Museum, Miami Science Museum, Museum of Contemporary ArtSony VAIO PCG-7152L battery, Vizcaya Museum and Gardens, Wolfsonian-FIU Museum and the Miami Cultural Center, home of the Miami Main Library. Miami is also the home of the world's largest art exhibition, dubbed the "Olympics of Art", Art Basel Miami. The event is held annually in December, and attracts thousands of visitors from around the worldSony VAIO PCG-7151L battery.

Parks

The Barnacle Historic State Park, built in 1891 in Miami's Coconut Grove neighborhood.

Miami's tropical weather allows for year-round outdoors activities. The city has numerous marinas, rivers, bays, canals, and the Atlantic Ocean, which make boating, sailing, and fishing popular outdoors activities. Biscayne Bay has numerous coral reefs which make snorkeling and scuba diving popular. There are over 80 parks and gardens in the city. 
Sony VAIO PCG-7148L battery The largest and most popular parks are Bayfront Park and Bicentennial Park (located in the heart of Downtown and the location of the American Airlines Arena and Bayside Marketplace), Fairchild Tropical Botanic Garden, Key Biscayne (Crandon Park and Bill Baggs Cape Florida State Park), Tropical Park, Peacock Park, Morningside Park, Virginia Key, and Watson Island.

Other popular cultural destinations in the area include Jungle Island, Zoo Miami, Miami Seaquarium, Coral Castle, St. Bernard de Clairvaux Church, and the Charles Deering EstateSony VPCW21M2E/WI battery.

Music

The city is a major music production city and attracts many annual music festivals, such as Ultra Music Festival

Miami music is varied. Cubans brought the conga and rumba to Miami from their homelands instantly popularizing it in American culture. Dominicans brought bachata, and merengue, while Colombians brought vallenato and cumbia, and Brazilians brought samba. West Indians and Caribbean people have brought reggae, soca, kompa, zouk, calypso, and steel pan to the area as wellSony VPCW21C7E battery.

In the early 1970s, the Miami disco sound came to life with TK Records, featuring the music of KC and the Sunshine Band, with such hits as "Get Down Tonight", "(Shake, Shake, Shake) Shake Your Booty" and "That's the Way (I Like It)"; and the Latin-American disco group, Foxy (band), with their hit singles "Get Off" and "Hot Number"Sony VPCW12S1E/WZ battery. Miami-area natives George McCrae and Teri DeSario were also popular music artists during the 1970s disco era. The Bee Gees moved to Miami in 1975 and have lived here ever since then. Miami-influenced, Gloria Estefan and the Miami Sound Machine, hit the popular music scene with their Cuban-oriented sound and had huge hits in the 1980s with "Conga" and "Bad Boys"Sony VPCW12S1E/W battery.

Miami is also considered a "hot spot" for dance music, Freestyle, a style of dance music popular in the 80's and 90's heavily influenced by Electro, hip-hop, and disco. Many popular Freestyle acts such as Pretty Tony, Debbie Deb, Stevie B, and Exposé, originated in Miami. Indie/folk acts Cat Power and Iron & Wine are based in the city, Sony VPCW12S1E/T battery while alternative hip hop artist Sage Francis, electro artist Uffie, and the electroclash duo Avenue D were born in Miami, but musically based elsewhere. Also, ska punk band Against All Authority is from Miami, and rock/metal bands Nonpoint and Marilyn Manson each formed in neighboring Fort Lauderdale. Popular Cuban American female recording artist, Ana Cristina, was born in Miami in 1985Sony VPCW12S1E/P battery, and became the first Hispanic person in history to perform the "Star Spangled Banner" at a presidential inauguration.

The 80's and 90's also brought the genre of high energy Miami Bass to dance floors and car subwoofers throughout the country. Miami Bass spawned artists like 2 Live Crew (featuring Uncle Luke), 95 South, Tag Team, 69 Boyz, Quad City DJ's, and Freak Nasty. Examples of these songs are "Whoomp! (There It Is)" by Tag Team in 1993Sony VPCW11S1E/W battery, "Tootsee Roll" by 69 Boyz in 1994, and "C'mon N' Ride It (The Train)" by the Quad City DJ's in 1996. These songs all reached the top 10 in the pop charts and gave Miami Bass a new commercial success.

Miami is also home to a vibrant techno and dance scene and hosts the Winter Music Conference, the largest dance event in the world, Ultra Music Festival and many electronica music-themed celebrations and festivals. Along with neighboring Miami BeachSony VPCW11S1E/T battery, Miami is home to nightclubs such as Space, Mansion, Parkwest, Ink, and Cameo. The city is known to be part of clubland, along with places such as Mykonos, Ibiza and Ayia Napa.

There are also several rap and hip hop artists out of Miami. They include Trick Daddy, Trina, Pitbull, Pretty Ricky, DJ Khaled, Flo-Rida, Jackie-O, Rick Ross, DJ Laz, and the Miami Bass group 2 Live CrewSony VPCW11S1E/P battery.

Media

See also: List of radio stations in Florida

The Miami Herald headquarters.

Miami has one of the largest television markets in the nation and the second largest in the state of Florida.[42] Miami has several major newspapers, the main and largest newspaper being The Miami Herald. El Nuevo Herald is the major and largest Spanish-language newspaper. Both The Miami Herald and El Nuevo Herald are Miami's and South Florida's main, major and largest newspapers and are both headquartered in Downtown Miami in Herald PlazaSony VPCYA1S1E/B battery.

Other major newspapers include Miami Today, headquartered in Brickell, Miami New Times, headquartered in Midtown, Miami Sun Post, South Florida Business Journal, Miami Times, and Biscayne Boulevard Times. An additional Spanish-language newspapers, Diario Las Americas also serve Miami. The Miami Herald is Miami's primary newspaper with over a million readers and is headquartered in Downtown in Herald PlazaSony VPCYA1V9E/B battery. Several other student newspapers from the local universities, such as the oldest, the University of Miami's The Miami Hurricane, Florida International University's The Beacon, Miami-Dade College's The Metropolis, Barry University's The Buccaneer, amongst others. Many neighborhoods and neighboring areas also have their own local newspapers such as the Aventura News, Coral Gables Tribune, Biscayne Bay Tribune, and the Palmetto Bay NewsSony VPCY22Z5008B battery.

A number of magazines circulate throughout the greater Miami area, including Miami Monthly, Southeast Florida's only city/regional; Ocean Drive, a hot-spot social scene glossy, and South Florida Business Leader.

Miami is also the headquarters and main production city of many of the world's largest television networks, record label companies, broadcasting companies and production facilities, such as Telemundo, TeleFutura, Galavisión, Mega TV, Univisión, Univision Communications, Inc. Sony VPCY21S1E/SI battery, Universal Music Latin Entertainment, RCTV International and Sunbeam Television. In 2009, Univisión announced plans to build new production studios in Miami, dubbed 'Univisión Studios'. Univisión Studios will be headquartered in Miami, and will produce programming for all of Univisión Communications' television networks. Sony VPCY21S1E/L battery

Miami is the twelfth largest radio market[44] and the seventeenth largest television market[45] in the United States. Television stations serving the Miami area include: WAMI (Telefutura), WBFS (My Network TV), WSFL (The CW), WFOR (CBS), WHFT (TBN), WLTV (Univision), WPLG (ABC), WPXM (ION), WSCV (Telemundo), WSVN (Fox), WTVJ (NBC), WPBT (PBS), and WLRN (also PBS) Sony VPCY21S1E/G battery.

Cuisine

The cuisine of Miami is a reflection of its diverse population, with a heavy influence especially from Caribbean cuisine and from Latin American cuisine. By combining the two with American cuisine, it has spawned a unique South Florida style of cooking known as Floribbean cuisine. Floribbean cuisine is widely available throughout Miami and South Florida, and can be found in restaurant chains such as Pollo TropicalSony VPCY11S1E/S battery.

Cuban immigrants in the 1960s brought the Cuban sandwich, medianoche, Cuban espresso, and croquetas, all of which have grown in popularity to all Miamians, and have become symbols of the city's varied cuisine. Today, these are part of the local culture, and can be found throughout the city in window cafés, particularly outside of supermarkets and restaurants. Sony VPCY11S1E battery Restaurants such as Versailles restaurant in Little Havana is a landmark eatery of Miami. Located on the Atlantic Ocean, and with a long history as a seaport, Miami is also known for its seafood, with many seafood restaurants located along the Miami River, and in and around Biscayne Bay.[48] Miami is also the home of restaurant chains such as Burger King, Tony Roma's and BenihanaSony VPCZ11X9E/B battery.

Accent

See also: North American English regional phonology

In Miami, a unique accent, commonly called the "Miami accent", is widely spoken. It developed mostly by second- or third-generation Hispanics, mostly Cuban-Americans, whose first language was English. It is very similar to accents in the Northeast, but contains a rhythm and pronunciation heavily influenced by Spanish. Sony VPCZ11Z9E/B battery

Sports

American Airlines Arena, home to the Miami Heat.

The Sony Ericsson Open, a major tennis tournament, is held in Miami annually

See also: U.S. cities with teams from four major sports

Miami's main four sports teams are the Miami Dolphins of the National Football League, the Miami Heat of the National Basketball Association, the Miami Marlins of Major League Baseball, and the Florida Panthers of the National Hockey League. As well as having all four major professional teams, Miami is also home to Miami FCSony VPCZ12M9E/B battery, Miami Tropics, the Sony Ericsson Open for professional tennis, numerous greyhound racing tracks, marinas, jai alai venues, and golf courses. The city streets has hosted professional auto races, the Miami Indy Challenge and later the Grand Prix Americas, whereas the Homestead-Miami Speedway oval located 35 miles southwest currently hosts NASCAR national racesSony VPCZ12X9E/X battery.

In 1946, the Miami Seahawks played in the All-America Football Conference for one season, 1946, and then folded. The city's first entry into the American Football League was the Miami Dolphins, which competed in the fourth AFL league from 1966–1969. In 1996, Miami acquired the AFL team the Sacramento Attack, which was renamed as the Miami HootersSony VPCZ12Z9E/X battery (due to its association with the Florida-based Hooters restaurant chain), and it played from 1993–1995. In 1996, the association with the chain was completed, and the team moved to West Palm Beach and renamed as the Florida Bobcats.

Currently, the Miami Heat and the Miami Marlins play their games within Miami's city limits. The Heat play their home games at the American Airlines Arena in Downtown Miami. The Miami Marlins home ballpark is Marlins ParkSony VPCZ138GA battery, located in the Little Havana section of the city on the site of the old Orange Bowl stadium.

The Miami Dolphins play their games at Sun Life Stadium in nearby Miami Gardens. The Orange Bowl, a member of the Bowl Championship Series, hosts their college football championship games at Sun Life Stadium. The stadium has also hosted the Super Bowl; the Miami metro area has hosted the game a total of ten times (five Super Bowls at the now Sun Life StadiumSony VPCZ13M9E/B battery, including Super Bowl XLI and five at the Miami Orange Bowl), tying New Orleans for the most games.

The Florida Panthers play in neighboring Broward County at the BankAtlantic Center in the city of Sunrise. Miami FC, Florida's only professional soccer team, plays at Tropical Park Stadium. Miami signed world-famed soccer player Romario in March 2006 to a one year deal. Miami is also home to Paso Fino horses, where competitions are held at Tropical Park Equestrian CenterSony VPCZ13M9E/X battery.

Miami is also the home of many college sports teams. The two largest are the University of Miami Hurricanes, whose football team formerly played at the Miami Orange Bowl from 1937 until 2008, moving to Sun Life Stadium subsequently, and Florida International University Golden Panthers whose football team plays at FIU StadiumSony VPCZ13V9E battery.

A number of defunct teams were located in Miami, including the Miami Floridians (ABA), Miami Matadors (ECHL), Miami Manatees (WHA2), Miami Gatos (NASL), Miami Screaming Eagles (WHA), Miami Seahawks (AAFC), Miami Sol (WNBA), Miami Toros (NASL), Miami Tropics (SFL), Miami Tropics (ABA), and the Miami Hooters (Arena Football League). The Miami Fusion, a defunct Major League Soccer team, played at Lockhart Stadium in nearby Broward CountySony VPCZ13X5003B battery.

Economy

Downtown is South Florida's main hub for finance, commerce and international business. Brickell Avenue has the largest concentration of international banks in the U.S.

As seen in 2006, the high-rise construction in Miami has inspired popular opinion of "Miami manhattanization"

The Port of Miami is the world's largest cruise ship port, and is the headquarters of many of the world's largest cruise companiesSony VPCZ13V9E/X battery

Miami is a major center of commerce, finance, and boasts a strong international business community. According to the ranking of world cities undertaken by the Globalization and World Cities Study Group & Network (GaWC) and based on the level of presence of global corporate service organizations, Miami is considered a "Beta− world city".[11] Miami has a Gross Metropolitan Product of $257 billion and is ranked 20th worldwide in GMPSony VPCZ13Z9E/X battery, and 11th in the United States.

Several large companies are headquartered in or around Miami, including but not limited to: Akerman Senterfitt, Alienware, Arquitectonica, Arrow Air, Bacardi, Benihana, Brightstar Corporation, Burger King, Celebrity Cruises, Carnival Corporation, Carnival Cruise Lines, CompUSA, Crispin Porter + Bogusky, Duany Plater-Zyberk & CompanySony VPCZ21M9E battery, Espírito Santo Financial Group, Fizber.com, Greenberg Traurig, Holland & Knight, Inktel Direct, Interval International, Lennar, Navarro Discount Pharmacies, Norwegian Cruise Lines, Oceania Cruises, Perry Ellis International, RCTV International, Royal Caribbean Cruise Lines, Ryder Systems, Seabourn Cruise Line, Sedano's, Telefónica USA, TeleFutura, TelemundoSony VPCZ21Q9E battery, Univision, U.S. Century Bank, Vector Group and World Fuel Services. Because of its proximity to Latin America, Miami serves as the headquarters of Latin American operations for more than 1400 multinational corporations, including AIG, American Airlines, Cisco, Disney, Exxon, FedEx, Kraft Foods, LEO Pharma Americas, Microsoft, Yahoo, Oracle, SBC Communications, Sony, Symantec, Visa International, and Wal-Mart. Sony VPCZ21V9E battery

Miami is a major television production center, and the most important city in the U.S. for Spanish language media. Univisión, Telemundo and TeleFutura have their headquarters in Miami, along with their production studios. The Telemundo Television Studios produces much of the original programming for Telemundo, such as their telenovelas and talk showsSony VPCEH3T9E battery. In 2011, 85% of Telemundo's original programming was filmed in Miami.[53] Miami is also a major music recording center, with the Sony Music Latin and Universal Music Latin Entertainment headquarters in the city, along with many other smaller record labels. The city also attracts many artists for music video and film shootingsSony VPCEH3N6E battery.

Since 2001, Miami has been undergoing a large building boom with more than 50 skyscrapers rising over 400 feet (122 m) built or currently under construction in the city. Miami's skyline is ranked third most impressive in the U.S., behind New York City and Chicago, and 19th in the world according to the Almanac of Architecture and Design.[54] The city currently has the eight tallest (as well as thirteen of the fourteen tallest) Sony VPCEH3N1E battery skyscrapers in the state of Florida, with the tallest being the 789-foot (240 m) Four Seasons Hotel & Tower.[55]

During the mid-2000s, the city witnessed its largest real estate boom since the Florida land boom of the 1920s. During this period, the city had well over a hundred approved high-rise construction projects in which 50 were actually built.[56] In 2007, however, the housing market crashed causing lots of foreclosures on houses. Sony VPCEH3D0E battery This rapid high-rise construction, has led to fast population growth in the city's inner neighborhoods, primarily in Downtown, Brickell and Edgewater, with these neighborhoods becoming the fastest-growing areas in the city. The Miami area ranks 8th in the nation in foreclosures.[58] In 2011, Forbes Magazine named Miami the second most miserable city in the United States due to its high foreclosure rate and past decade of corruption among public officials. Sony VPCEH3B1E battery In 2012, Forbes Magazine named Miami the most miserable city in the United States because of a crippling housing crisis that has cost multitudes of residents their homes and jobs. The metro area has one of the highest violent crime rates in the country and workers face lengthy daily commutesSony VPCEH2Z1E battery.

Miami International Airport and the Port of Miami are among the nation's busiest ports of entry, especially for cargo from South America and the Caribbean. The Port of Miami is the world's busiest cruise port, and MIA is the busiest airport in Florida, and the largest gateway between the United States and Latin America. Additionally, the city has the largest concentration of international banks in the countrySony VPCEH2S9E battery, primarily along Brickell Avenue in Brickell, Miami's financial district. Due to its strength in international business, finance and trade, many international banks have offices in Downtown such as Espírito Santo Financial Group, which has its U.S. headquarters in Miami. Miami was also the host city of the 2003 Free Trade Area of the Americas negotiations, and is one of the leading candidates to become the trading bloc's headquartersSony VPCEH2Q1E battery.

As of 2011, the Port of Miami accounts for 176,000 jobs and has an annual economic impact in Miami of $18 billion. It is the 11th-largest cargo container port in the United States. In 2010, a record 4.33 million passengers traveled through the Port of Miami. One in seven of all the world’s cruise passengers start from Miami. Sony VPCEH2P0E battery

The Civic Center has the country's second-largest concentration of medical and research facilities. It is the center of Miami's growing biotechnology sectors.[60]

Tourism is also an important industry in Miami. Along with finance and business, the beaches, conventions, festivals and events draw over 38 million visitors annually into the city, from across the country and around the world, spending $17.1 billion. The Art Deco District in South Beach, is reputed as one of the most glamorous in the world for its nightclubs, beaches, historical buildings, and shopping. Annual events such as the Sony Ericsson OpenSony VPCEH2N1E battery, Art Basel, Winter Music Conference, South Beach Wine & Food Festival, and Mercedes-Benz Fashion Week Miami attract millions to the metropolis every year.

Miami is the home to the National Hurricane Center and the headquarters of the United States Southern Command, responsible for military operations in Central and South America. In addition to these roles, Miami is also an industrial center, especially for stone quarrying and warehousing. These industries are centered largely on the western fringes of the city near Doral and HialeahSony VPCEH2M9E battery.

According to the U.S. Census Bureau, in 2004, Miami had the third highest incidence of family incomes below the federal poverty line in the United States, making it the third poorest city in the USA, behind only Detroit, Michigan (ranked #1) and El Paso, Texas (ranked #2). Miami is also one of the very few cities where its local government went bankrupt, in 2001. Sony VPCEH2M1E batteryHowever, since that time, Miami has experienced a revival: in 2008, Miami was ranked as "America's Cleanest City" according to Forbes for its year-round good air quality, vast green spaces, clean drinking water, clean streets and city-wide recycling programs.[15] In a 2009 UBS study of 73 world cities, Miami was ranked as the richest city in the United States (of four U.S. cities included in the survey) and the world's fifth-richest city, in terms of purchasing power. Sony VPCEH2L9E battery

Demographics

Miami is the 42nd most populous city in the U.S. The Miami metropolitan area, which includes Miami-Dade, Broward and Palm Beach counties, had a combined population of more than 5.5 million people, ranked seventh largest in the United States,[66] and is the largest metropolitan area in the Southeastern United States. As of 2008, the United Nations estimates that the Miami Urban Agglomeration is the 44th-largest in the world.Sony VPCEH2J1E battery

As of 2000, in terms of national origin and/or ethnic origin, 34.1% of the populace was Cuban,[68] while 5.6% of the city's population was Nicaraguan,[69] 5.5% of the population was Haitian,[70] 3.3% of the population was Honduran,[71] 1.7% of all residents were Dominican,[72] and 1.6% of the population was Colombian.[73] In 2004, the United Nations Development Program Sony VPCEH2H1E battery (UNDP) ranked Miami first in terms of percentage of residents born outside of the country it is located in (59%), followed by Toronto (50%).

As of 2010, there were 183,994 households of which 14.0% were vacant.[64] As of 2000, 26.3% had children under the age of 18 living with them, 36.6% were married couples living together, 18.7% have a female head of household with no husband present, and 37.9% were non-familiesSony VPCEH2F1E battery. 30.4% of all households were made up of individuals and 12.5% had someone living alone who was 65 years of age or older. The average household size was 2.61 and the average family size was 3.25. The age distribution was 21.7% under the age of 18, 8.8% from 18 to 24, 30.3% from 25 to 44, 22.1% from 45 to 64, and 17.0% who were 65 years of age or older. The median age was 38 yearsSony VPCEH2E0E battery. For every 100 females there were 98.9 males. For every 100 females age 18 and over, there were 97.3 males.

In 2009, the median income for a household in the city was $29,812, and the median income for a family was $33,814. The per capita income for the city was $19,846. About 21.7% of families and 26.3% of the population were below the poverty lineSony VPCEH2D0E battery.

In 1960, non-Hispanic whites represented 80% of Miami-Dade county's population.[74] In 1970, the Census Bureau reported Miami's population as 45.3% Hispanic, 32.9% non-Hispanic White, and 22.7% Black.[75] Miami's explosive population growth has been driven by internal migration from other parts of the country, primarily up until the 1980s, as well as by immigrationSony VPCEH2C0E battery, primarily from the 1960s to the 1990s. Today, immigration to Miami has slowed significantly and Miami's growth today is attributed greatly to its fast urbanization and high-rise construction, which has increased its inner city neighborhood population densities, such as in Downtown, Brickell, and Edgewater, where one area in Downtown alone saw a 2,069% increase in population in the 2010 CensusSony VPCEH1Z1E battery. Miami is regarded as more of a multicultural mosaic, than it is a melting pot, with residents still maintaining much of, or some of their cultural traits. The overall culture of Miami is heavily influenced by its large population of Hispanics, and Blacks, mainly from the Caribbean islands.

Plymouth Congregational Church in Coconut Grove.

There has been a Norwegian Seamen's church in Miami since the early 1980s. In November 2011, Crown Princess Mette-Marit opened a new building for the church. The church was built as a center for the 10,000 Scandinavians that live in FloridaSony VPCEH1S9E battery. Around 4,000 of them are Norwegian. The church is also an important place for the 150 Norwegians that work at Disney World.[76]

Languages

As of 2000, speakers of Spanish as their first language accounted for 66.75% of residents, English by 25.45%, Haitian Creole by 5.20%, and French speakers comprised 0.76% of the population.[77]

Other languages that were spoken throughout the city include Portuguese at 0.41%, German at 0.18%, Italian at 0.16%, Arabic at 0.15%, Chinese at 0.11%, and Greek at 0.08% of the populationSony VPCEH1S8E battery. Miami also has one of the largest percentage populations in the U.S. that have residents who speak first languages other than English at home (74.55%).

Due to English-speakers moving away from the area, the percentage of residents who speak only English is expected to continue to decline.

Civic engagement

Organizations such as the Miami-Dade Salvation Army and its iconic Red Kettle Christmas Campaign, Hands On Miami, City Year Miami, Human Services Coalition of South Florida, and Citizens for a Better South Florida, among many other organizations have been working to engage Miamians in volunteerismSony VPCEH1S1E battery.

Government

Miami City Hall in Dinner Key.

Main article: Government of the City of Miami

The government of the City of Miami (proper) uses the mayor-commissioner type of system. The city commission consists of five commissioners, are elected from single member districts. The city commission constitutes the governing body with powers to pass ordinances adopt regulations and exercise all powers conferred upon the city in the city charterSony VPCEH1S0E battery.The mayor is elected at large and appoints a city manager. The City of Miami is governed by Mayor Tomás Regalado and 5 City commissioners which oversee the five districts in the City. It holds regular meetings in the City Hall of Miami located in 3500 Pan American Drive Miami, Florida 33133 in the neighborhood of Coconut Grove on Dinner KeySony VPCEH1M9E battery.

City council

See also: List of mayors of Miami

Tomás Regalado – Mayor of the City of Miami

Wifredo "Willy" Gort – City of Miami Commissioner, District 1

Marc Sarnoff – City of Miami Commissioner, District 2

Frank Carollo – City of Miami Commissioner, District 3

Francis Suarez – City of Miami Commissioner, District 4

Richard P. Dunn – City of Miami Commissioner, District 5

Education

Public schools

Main article: Miami-Dade County Public Schools

Miami Senior High School, Miami's oldest continuously-used high school structure

Florida International University has the largest enrollment of any university in South Florida, and is one of the state's primary research universitiesSony VPCEH1M1E battery.

Public schools in Miami are governed by Miami-Dade County Public Schools, which is the largest school district in Florida and the fourth-largest in the United States. As of September 2008 it has a student enrollment of 385,655 and over 392 schools and centers. The district is also the largest minority public school system in the country, with 60% of its students being of Hispanic origin, 28% Black or West Indian American, 10% White (non-Hispanic) Sony VPCEH1L9E battery and 2% non-white of other minorities.[79] Miami is home to some of the nation's best high schools, such as Design and Architecture High School, ranked the nation's best magnet school, MAST Academy, Coral Reef High School, ranked 20th-best public high school in the U.S., Miami Palmetto High School, and the New World School of the Arts.[80] M-DCPS is also one of a few public school districts in the United States to offer optional bilingual education in SpanishSony VPCEH1L8E battery, French, German, Haitian Creole, and Mandarin Chinese.

Private schools

Miami is home to several well known Roman Catholic, Jewish and non-denominational private schools. The Archdiocese of Miami operates the city's Catholic private schools, which include: St. Hugh Catholic School, St. Agatha Catholic School, St. Theresa School, Immaculata-Lasalle High School, Monsignor Edward Pace High School, Archbishop Curley-Notre Dame High School, St. Brendan High School, amongst numerous other Catholic elementary and high schoolsSony VPCEH1L0E battery.

All-boys Catholic college preparatory schools are Christopher Columbus High School and Belen Jesuit Preparatory School. All-girls Catholic preparatory schools are Carrollton School of the Sacred Heart and Our Lady of Lourdes Academy.

Non-denominational private schools in Miami are Ransom Everglades, Gulliver Preparatory School, and Miami Country Day School. Other schools in the area include Samuel Scheck Hillel Community Day SchoolSony VPCEH1J8E battery, Dade Christian School, Palmer Trinity School, and Westminster Christian School.

Colleges and universities

Founded in 1925, the University of Miami is the oldest college in Florida south of Winter Park.

Miami has over 200,000 students enrolled in local colleges and universities, placing it seventh in the nation in per capita university enrollment. In 2010, the city's four largest colleges and universities (MDC, FIU, UM, and Barry) graduated 28,000 students. Sony VPCEH1J1E battery

Colleges and universities in and around Miami:

Barry University (private)

Carlos Albizu University (private)

Florida International University (FIU) (public)

Florida Memorial University (private)

Johnson and Wales University (private)

Keiser University (private)

Manchester Business School (satellite location, UK public)

Miami Culinary Institute (public)

Miami Dade College (public)

Miami International University of Art & Design (private)

Nova Southeastern University (private)

St. Thomas University (private)

Talmudic University (private)

University of Miami (private)

Overall, amongst Miamians 25 years and older, 67% had a high school diploma, and 22% had a bachelors degree or higher. Sony VPCEH1E1E battery

In 2011, Miami was ranked as the sixth most-read city in the U.S. with high book sales.[83]

Professional training programs

Miami is also home to both for-profit and nonprofit organizations that offer a range of professional training and other, related educational programs. Per Scholas, for example is a nonprofit organization that offers free professional certification training directed towards successfully passing CompTIA A+ and Network+ certification exams as a route to securing jobs and building careersSony VPCEH1AJ battery.

Transportation

Main article: Transportation in Miami

Airports

Miami International Airport, serves as the primary international airport of the Greater Miami Area. One of the busiest international airports in the world, Miami International Airport caters to over 35 million passengers a year. Identifiable locally, as well as several worldwide authorities, as MIA or KMIA, the airport is a major hub and the single largest international gateway for American Airlines, the world's second-largest passenger air carrierSony VPCCA3S1E battery. Miami International is the busiest airport in Florida, and is the United States' second-largest international port of entry for foreign air passengers behind New York's John F. Kennedy International Airport, and is the seventh-largest such gateway in the world. The airport's extensive international route network includes non-stop flights to over seventy international cities in North and South America, Europe, Asia, and the Middle EastSony VPCCA3E1E battery.

Alternatively, nearby Fort Lauderdale-Hollywood International Airport also serves commercial traffic in the Miami area. Opa-locka Airport in Opa-locka and Kendall-Tamiami Airport in an unincorporated area serve general aviation traffic in the Miami area.

Port of Miami

The Royal Caribbean International headquarters at the Port of Miami.

Miami is home to one of the largest ports in the United States, the Port of Miami. It is the largest cruise ship port in the world. The port is often called the "Cruise Capital of the World" and the "Cargo Gateway of the Americas".Sony VPCCA2Z0E battery It has retained its status as the number one cruise/passenger port in the world for well over a decade accommodating the largest cruise ships and the major cruise lines. In 2007, the port served 3,787,410 passengers.[89] Additionally, the port is one of the nation's busiest cargo ports, importing 7.8 million tons of cargo in 2007.[89] Among North American ports, it ranks second only to the Port of South Louisiana in New Orleans in terms of cargo tonnage imported/exported from Latin AmericaSony VPCCA2S1E battery. The port is on 518 acres (2 km2) and has 7 passenger terminals. China is the port's number one import country, and Honduras is the number one export country. Miami has the world's largest amount of cruise line headquarters, home to: Carnival Cruise Lines, Celebrity Cruises, Norwegian Cruise Line, Oceania Cruises, and Royal Caribbean International.

On May 24, 2010, construction began on the $1 billion Miami port tunnel that will serve the Port of Miami. Sony VPCCA2S0E battery

Public transportation

The Miami Metrorail is the city's rapid transit system and connects the city's central core with its outlying suburbs

Tri-Rail is Miami's commuter rail that runs north-south from Miami's suburbs in West Palm Beach to Miami International Airport.

Main article: Miami-Dade Transit

Public transportation in Miami is operated by Miami-Dade Transit and SFRTA, and includes commuter rail (Tri-Rail), heavy-rail rapid transit (Metrorail), an elevated people mover (Metromover), and buses (Metrobus). Miami has Florida's highest transit ridership as about 17% of Miamians use transit on a daily basis. Sony VPCCA2AJ battery

Miami's heavy-rail rapid transit system, Metrorail, is an elevated system comprising 22 stations on a 22-mile (35 km)-long line. Metrorail runs from the western suburbs of Hialeah and Medley through the Civic Center, Downtown, Brickell, Coconut Grove, Coral Gables, South Miami and ends in the southern suburban neighborhood of KendallSony VPCCA1S1E/W battery; construction on a direct Metrorail connection to Miami International Airport began in 2009 with expected passenger service beginning in early 2012.[92] A free, elevated people mover, Metromover, operates 21 stations on three different lines in Downtown, with a station at roughly every two blocks of Downtown and Brickell. Several expansion projects are being funded by a transit development sales tax surcharge throughout Miami-Dade CountySony VPCCA1S1E/P battery.

Tri-Rail, a commuter rail system operated by the South Florida Regional Transportation Authority (SFRTA), runs from Miami International Airport northward to West Palm Beach, making eighteen stops throughout Miami-Dade, Broward, and Palm Beach counties.

Construction is currently underway on the Miami Intermodal Center and Miami Central Station, a massive transportation hub servicing Metrorail, Amtrak, Tri-Rail, MetrobusSony VPCCA1S1E/G battery, Greyhound Lines, taxis, rental cars, MIA Mover, private automobiles, bicycles and pedestrians adjacent to Miami International Airport. Completion of the Miami Intermodal Center is expected to be completed by winter 2011, and will serve over 150,000 commuters and travelers in the Miami area. Phase I of Miami Central Station is scheduled to begin service in the spring of 2012, and Phase II in 2013Sony VPCCA1S1E/D battery.

Two new light rail systems, Baylink and the Miami Streetcar, have been proposed and are currently in the planning stage. BayLink would connect Downtown with South Beach, and the Miami Streetcar would connect Downtown with Midtown.

Rail

Miami is the southern terminus of Amtrak's Atlantic Coast services, running two lines, the Silver Meteor and the Silver Star, both terminating in New York City. The Miami Amtrak Station is located in the suburb of Hialeah near the Tri-Rail/Metrorail Station on NW 79 St and NW 38 AveSony VPCCA1S1E/B battery. Current construction of the Miami Central Station will move all Amtrak operations from its current out-of-the-way location to a centralized location with Metrorail, MIA Mover, Tri-Rail, Miami International Airport, and the Miami Intermodal Center all within the same station closer to Downtown. The station is expected to be completed by 2012.

Florida High Speed Rail was planned to connect Miami with Orlando and Tampa in a single line, but was canceled in 2011Sony VPCCA1S1E battery.

Road

The Venetian Causeway (left) and MacArthur Causeway (right) connect Downtown and South Beach, Miami Beach.

Miami's road system is based along the numerical "Miami Grid" where Flagler Street forms the east-west baseline and Miami Avenue forms the north-south meridian. The corner of Flagler Street and Miami Avenue is in the middle of Downtown in front of the Downtown Macy's (formerly the Burdine's headquarters) Sony VPCCA1C5E battery. The Miami grid is primarily numerical so that, for example, all street addresses north of Flagler Street and west of Miami Avenue have "NW" in their address. Because its point of origin is in Downtown which is close to the coast, therefore, the "NW" and "SW" quadrants are much larger than the "SE" and "NE" quadrants. Many roads, especially major ones, are also named Sony VPCCA1AHJ battery (e.g., Tamiami Trail/SW 8th St), although, with a few notable exceptions (e.g., Coral Way), the number is in more common usage among locals.

All streets and avenues in Miami-Dade County follow the Miami Grid, with a few exceptions, most notably Coral Gables, Hialeah, and Miami Beach. Some neighborhoods, such as The Roads, is thusly named because its streets run off the Miami Grid in a 45-degree angle, and therefore all named roadsSony VPCCA1AGJ battery.

Miami-Dade County is served by four Interstate Highways (I-75, I-95, I-195, I-395) and several U.S. Highways including U.S. Route 1, U.S. Route 27, U.S. Route 41, and U.S. Route 441.

Some of the major Florida State Roads (and their common names) serving Miami are:

SR 112 (Airport Expressway): Interstate 95 to MIA

SR 821 (The HEFT or Homestead Extension of the Florida Turnpike): SR 91/Miami Gardens to U.S. Route 1/Florida City) Sony VPCCA1AFJ battery

SR 826 (Palmetto Expressway): Golden Glades Interchange to U.S. Route 1/Pinecrest

SR 836 (Dolphin Expressway): Downtown to SW 137th Ave via MIA

SR 874 (Don Shula Expressway): 826/Bird Road to Homestead Extension of Florida's Turnpike/Kendall

SR 878 (Snapper Creek Expressway): SR 874/Kendall to U.S. Route 1/Pinecrest & South Miami

SR 924 (Gratigny Parkway) Miami Lakes to Opa-lockaSony VPCCA190 battery

Miami has six major causeways that span over Biscayne Bay connecting the western mainland, with the eastern barrier islands along the Atlantic Ocean. The Rickenbacker Causeway is the southernmost causeway and connects Brickell to Virginia Key and Key Biscayne. The Venetian Causeway and MacArthur Causeway connect Downtown with South BeachSony VAIO VPCF11Z1E battery. The Julia Tuttle Causeway connects Midtown and Miami Beach. The 79th Street Causeway connects the Upper East Side with North Beach. The northernmost causeway, the Broad Causeway, is the smallest of Miami's six causeways, and connects North Miami with Bal Harbour.

In 2007, Miami was identified as having the rudest drivers in the United States, the second year in a row to have been cited, in a poll commissioned by automobile club AutoVantage.[94] Miami is also consistently ranked as one of the most dangerous cities in the United States for pedestrians. Sony VAIO VPCF11S1E battery

Bicycling

In recent years the city government, under Mayor Manny Diaz, has taken an ambitious stance in support of bicycling in Miami for both recreation and commuting. Every month, the city hosts "Bike Miami", where major streets in Downtown and Brickell are closed to automobiles, but left open for pedestrians and bicyclists. The event began in November 2008Sony VAIO VPCF11M1E/H battery, and has doubled in popularity from 1,500 participants to about 3,000 in the October 2009 Bike Miami. This is the longest running such event in the US. In October 2009, the city also approved an extensive 20-year plan for bike routes and paths around the city. The city has begun construction of bike routes as of late 2009, and ordinances requiring bike parking in all future construction in the city became mandatory as of October 2009. Sony VAIO VPCF11M1E battery

In 2010, Miami was ranked as the 44th most bike-friendly city in the US according to Bicycling Magazine.[97]

Walkability

A 2011 study by Walk Score ranked Miami the eighth most walkable of the fifty largest cities in the United States.

In popular culture

View of the "Moon over Miami", a famous phrase that has inspired many pop culture items, including a movie, TV series, and songSony VAIO VPCF21ZHJ battery.

In film and television

See also: List of films and television shows set in Miami

Miami is a center for television and film production. The city has acted as the backdrop for many movies, and many television shows, telenovellas, and awards shows have been set or filmed in Miami. In the mid-2000s, Miami started to become a popular backdrop for reality television shows. Additionally, Miami is a major center, worldwide, for Spanish-language television and film productionSony VAIO VPCF21Z1E/BI battery.

In music

See Miami (Music)

Miami has inspired the names of musical groups as well as of numerous albums and song titles. For example, the late country singer Keith Whitley (1955–1989) sang a song called "Miami, My Amy", about a special woman from Miami; the song is one of his biggest hits to this day. Sony VAIO VGN-CS33H battery

In video games

The video games, Grand Theft Auto: Vice City (which became one of the best selling video games in 2002)[100] and Grand Theft Auto: Vice City Stories, take place in Vice City, a fictional city inspired by Miami, which includes some of the same architecture and geography. The game also includes characters who speak Haitian Creole and Spanish, as do many people found in MiamiSony VAIO VGN-CS33H/Z battery.

Dell, Inc. (NASDAQ: DELL) is an American multinational computer technology corporation based in 1 Dell Way, Round Rock, Texas, United States, that develops, sells and supports computers and related products and services. Bearing the name of its founder, Michael Dell, the company is one of the largest technological corporations in the worldSony VAIO PCG-9Z2L battery, employing more than 103,300 people worldwide. Dell is listed at number 41 in the Fortune 500 list. It is the third largest PC maker in the world after HP and Lenovo.

Dell has grown by both increasing its customer base and through acquisitions since its inception; notable mergers and acquisitions including Alienware (2006) and Perot Systems (2009). As of 2009, the company sold personal computers, servers, data storage devices, network switches, software, and computer peripherals. Dell also sells HDTVs, camerasSony VAIO PCG-9Z1L battery, printers, MP3 players and other electronics built by other manufacturers. The company is well known for its innovations in supply chain management and electronic commerce.

Fortune Magazine listed Dell as the sixth largest company in Texas by total revenue.[5] It is the second largest non-oil company in Texas – behind AT&T – and the largest company in the Austin, Texas areaSony VAIO PCG-9131L battery.

History

Main article: History of Dell

Dell traces its origins to 1984, when Michael Dell created PCs Limited while a student at the University of Texas at Austin. The dorm-room headquartered company sold IBM PC-compatible computers built from stock components.[7] Dell dropped out of school in order to focus full-time on his fledgling business, after getting about $300,000 in expansion-capital from his familySony VAIO PCG-8161L battery.

In 1985, the company produced the first computer of its own design, the "Turbo PC", which sold for US$795.[8] PCs Limited advertised its systems in national computer magazines for sale directly to consumers and custom assembled each ordered unit according to a selection of options. The company grossed more than $73 million in its first year of operationSony VAIO PCG-8152L battery.

The company changed its name to "Dell Computer Corporation" in 1988 and began expanding globally. In June 1988, Dell's market capitalization grew by $30 million to $80 million from its June 22 initial public offering of 3.5 million shares at $8.50 a share.[9] In 1992, Fortune magazine included Dell Computer Corporation in its list of the world's 500 largest companies, making Michael Dell the youngest CEO of a Fortune 500 company ever. Sony VAIO PCG-8141L battery

Growth in 1990s and early 2000s

From 1997 to 2004, Dell enjoyed steady growth and it gained market share from competitors even during industry slumps.[11]

In 1996, Dell began selling computers through its website, and in 2002, it expanded its product line to include televisions, handhelds, digital audio players, and printers. Dell's first acquisition occurred in 1999 with the purchase of ConvergeNet TechnologiesSony VAIO PCG-8131L battery.

Dell surpassed Compaq to become the largest PC manufacturer in 1999. In 2002, when Compaq merged with Hewlett Packard (the 4th place PC maker), the combined Hewlett Packard took the top spot but struggled and Dell soon regained its lead.

In 2003, the company was rebranded as simply "Dell Inc." to recognize the company's expansion beyond computersSony VAIO PCG-81312L battery.

In 2004, Michael Dell resigned as CEO while retaining the title of Chairman, handing the CEO title to Kevin Rollins who was the President and COO. Under Rollins, Dell began to loosen its ties to Microsoft and Intel, the two companies which were responsible for Dell's dominance in the PC business. During that time, Dell acquired Alienware, which introduced several new items to Dell productsSony VAIO PCG-81214L battery, including AMD microprocessors. To prevent cross-market products, Dell continues to run Alienware as a separate entity, but still a wholly owned subsidiary.[12]

Missed expectations and return of founder

However in 2005, while earnings and sales grew, sales growth slowed considerably, and the company stock lost 25% of its value that year.

The slowing sales growth has been attributed to the maturing PC market, which constituted 66% of Dell's sales, and analysts suggested that Dell needed to make inroads into non-PC businesses segments such as storage, services and serversSony VAIO PCG-81115L battery. Dell's price advantage was tied to its ultra-lean manufacturing for desktop PCs, however this became less important as the market shifted to laptops, and as rivals such as Hewlett-Packard and Acer made their PC operations more efficient. Throughout the entire PC industry, declines in prices along with commensurate increases in performance meant that Dell had fewer opportunities to upsell to their customers Sony VAIO PCG-81114L battery (a lucruative strategy of encouring buyers to upgrade processor or memory), and as a result the company was selling a greater proportion of inexpensive PCs than before which eroded profit margins.[11]

There has also been a decline in consumers purchasing PCs through the Web or on the phone, as increasing numbers were visiting consumer electronics retail stores. As well, many analysts were looking to innovating companies as the next source of growth in the technology sectorSony VAIO PCG-81113L battery. Dell's low spending on R&D relative to its revenue (compared to Apple Inc.) which worked well in the commoditized PC market prevented it from making inroads into more lucrative segments such as MP3 players.[13]

Dell's reputation for poor customer service, which was exacerbated as it moved call centres offshore and as its growth outstripped its technical support infrastructure, came under increasing scrutiny on the WebSony VAIO PCG-7142L battery. There was also criticism that it used faulty components for its PCs.[14] There was also a battery recall in August 2006, as a result of a Dell laptop catching fire which caused much negative attention for the company, although later Sony was found to be responsible for the faulty batteries.[11]

2006 marked the first year that Dell's growth was slower than the PC industry as a whole. By the fourth quarter of 2006, Dell lost its title of the largest PC manufacturer to rival Hewlett Packard which was invigorated thanks to a restructuring initiated by their CEO Mark HurdSony VAIO PCG-7141L battery.

After four out of five quarterly earnings reports were below expectations, Rollins resigned in January 2007 and founder Michael Dell assumed the role of CEO again. Dell announced a change campaign called "Dell 2.0," reducing headcount and diversifying the company's product offerings.

Recent plans and acquisitionsSony VAIO PCG-71111L battery

In 2006, Dell acquired Alienware, a manufacturer of high-end PCs popular with gamers.

The company acquired EqualLogic on January 28, 2008, to gain a foothold in the iSCSI storage market. Because Dell already had an efficient manufacturing process, integrating EqualLogic's products into the company drove manufacturing prices down.[19]

In 2009, Dell acquired Perot Systems, a technology services and outsourcing company, mainly active in the health-sector, founded by former presidential hopeful H. Ross PerotSony VAIO PCG-61411L battery

In 2009, Dell acquired Perot Systems, based in Plano, Texas, in a reported $3.9 billion deal.[20] Perot Systems provided Dell with applications development, systems integration, and strategic consulting services through its operations in the U.S. and 10 other countries. In addition, the acquisition of Perot brought a variety of business process outsourcing services, including claims processing and call center operations. Sony VAIO PCG-61112L battery

On February 10, 2010, the company acquired KACE Networks a leader in Systems Management Appliances. The terms of the deal were not disclosed.[22]

On August 16, 2010, Dell announced plans to acquire the data storage company 3PAR.[23] On September 2, Hewlett-Packard offered $33 a share for 3PAR, which Dell declined to match.[24]

On November 2, 2010, Dell acquired Software-as-a-Service (SaaS) integration leader Boomi. Terms of the deal were not disclosed. Sony VAIO PCG-61111L battery

In February 2011 the acquisition of Compellent by Dell was completed after the initial announcement of Dell's intention to buy the company was announced on 13 December, 2010

On Friday February 24, 2012 Dell acquired Backup and Disaster Recovery software solution AppAssure Software of Reston, VA. AppAssure delivered 194 percent revenue growth in 2011 and over 3500% growth in the prior 3 yearsSony VAIO PCG-5T4L battery. AppAssure supports physical servers and VMware, Hyper-V and XenServer. The deal represents the first acquisition since Dell formed its software division under former CA CEO John Swainson. Dell added that it will keep AppAssure’s 230 employees and invest in the company.

Dell is headquartered in Round Rock, Texas

In March 2012, USA Today said that Dell agreed to buy SonicWall, which acquisition was completed 9th May 2012[26], a company with 130 patents. SonicWall which develops security products, is a network and data security providerSony VAIO PCG-5T3L battery.

On 2 April, 2012, Dell announced that it wants to acquire Wyse, global market-leader for thin client systems[28]

On 3 April, 2012, Dell announced that it has acquired Clerity Solutions. Clerity, a company offering services for application (re)hosting, was formed in 1994 and has it headquarters in Chicago. At the time of the take-over aprox. 70 people were working for the companySony VAIO PCG-5T2L battery.

Dell facilities

Dell's headquarters is located in Round Rock, Texas.[30] As of 2010 the company employs about 16,000 people in the facility,[31] which has 2,100,000 square feet (200,000 m2) of space.[32] As of 1999 almost half of the general fund of the City of Round Rock originates from sales taxes generated from the Dell headquarters. Sony VAIO PCG-5S3L battery

Dell previously had its headquarters in the Arboretum complex in northern Austin, Texas.[34][35] In 1989 Dell occupied 127,000 square feet (11,800 m2) in the Arboretum complex.[36] In 1990 Dell had 1,200 employees in its headquarters.[34] In 1993 Dell submitted a document to Round Rock officials, titled "Dell Computer Corporate Headquarters, Round RockSony VAIO PCG-5S2L battery, Texas, May 1993 Schematic Design." Despite the filing, during that year the company said that it was not going to move its headquarters.[37] In 1994 Dell announced that it was moving most of its employees out of the Arboretum, but that it was going to continue to occupy the top floor of the Arboretum and that the company's official headquarters address would continue to be the ArboretumSony VAIO PCG-5S1L battery. The top floor continued to hold Dell's board room, demonstration center, and visitor meeting room. Less than one month prior to August 29, 1994, Dell moved 1,100 customer support and telephone sales employees to Round Rock.[38] Dell's lease in the Arboretum had been scheduled to expire in 1994.[39]

The company sponsors Dell Diamond, the home stadium of the Round Rock Express, the AAA minor league baseball affiliate of the Texas Rangers major league baseball teamSony VAIO PCG-5R2L battery

By 1996 Dell was moving its headquarters to Round Rock.[40] As of January 1996 3,500 people still worked at the current Dell headquarters. One building of the Round Rock headquarters, Round Rock 3, had space for 6,400 employees and was scheduled to be completed in November 1996.[41] In 1998 Dell announced that it was going to add two buildings to its Round Rock complexSony VAIO PCG-5R1L battery, adding 1,600,000 square feet (150,000 m2) of office space to the complex.[42]

In 2000 Dell announced that it would lease 80,000 square feet (7,400 m2) of space in the Las Cimas office complex in unincorporated Travis County, Texas, between Austin and West Lake Hills, to house the company's executive offices and corporate headquarters. 100 senior executives were scheduled to work in the building by the end of 2000. Sony VAIO PCG-5P4L batteryIn January 2001 the company leased the space in Las Cimas 2, located along Loop 360. Las Cimas 2 housed Dell's executives, the investment operations, and some corporate functions. Dell also had an option for 138,000 square feet (12,800 m2) of space in Las Cimas 3.[44] After a slowdown in business required reducing employees and production capacity, Dell decided to sublease its offices in two buildings in the Las Cimas office complex. Sony VAIO PCG-5P2L battery In 2002 Dell announced that it planned to sublease its space to another tenant; the company planned to move its headquarters back to Round Rock once a tenant was secured.[44] By 2003 Dell moved its headquarters back to Round Rock. It leased all of Las Cimas I and II, with a total of 312,000 square feet (29,000 m2), for about a seven year period after 2003. By that year roughly 100,000 square feet (9,300 m2) of that space was absorbed by new subtenants. Sony VAIO PCG-5N4L battery

In 2008 Dell switched the power sources of the Round Rock headquarters to more environmentally friendly ones, with 60% of the total power coming from TXU Energy wind farms and 40% coming from the Austin Community Landfill gas-to-energy plant operated by Waste Management, Inc. Sony VAIO PCG-5N2L battery

Dell facilities in the United States are located in Austin, Texas; Nashua, New Hampshire; Nashville, Tennessee; Oklahoma City, Oklahoma; Peoria, Illinois; Winston-Salem, North Carolina; Eden Prairie, Minnesota (Dell Compellent); and Miami, Florida. Facilities located abroad include Penang, Malaysia; Xiamen, China; Bracknell, UK; Manila, Philippines[47] Chennai, India; Sony VAIO PCG-51513L battery Hortolandia and Porto Alegre, Brazil; Bratislava, Slovakia; Łódź, Poland,[49] Panama City in Panama, Dublin and Limerick, Ireland.[50]

The US and India are the only countries which have all of Dell's business functions and provide support globally: Research and Development, manufacturing, finance, analysis, customer care.

Products

Scope and brands

Dell's tagline 'Yours is Here', as seen at their Mall of Asia branch in Pasay City, Philippines

The corporation markets specific brand names to different market segmentsSony VAIO PCG-51511L battery.

Its Business/Corporate class represent brands where the company advertising emphasizes long life-cycles, reliability, and serviceability. Such brands include:

OptiPlex (office desktop computer systems)

Vostro (office/small business desktop and notebook systems)

n Series (desktop and notebook computers shipped with Linux or FreeDOS installed)

Latitude (business-focused notebooks)

Precision (workstation systems and high-performance notebooks),[52]

PowerEdge (business servers) Sony VAIO PCG-51412L battery

PowerVault (direct-attach and network-attached storage)

PowerConnect (network switches)

Dell Compellent (storage area networks)

EqualLogic (enterprise class iSCSI SANs)

Dell's Home Office/Consumer class emphasizes value, performance, and expandability. These brands include:

Inspiron (budget desktop and notebook computers)

Studio (mainstream desktop and laptop computers)

XPS (high-end desktop and notebook computers)

Studio XPS (high-end design-focus of XPS systems and extreme multimedia capability)

Alienware (high-performance gaming systems) Sony VAIO PCG-51411L battery

Adamo (high-end luxury laptop)

Dell EMR (electronic medical records)

Dell's Peripherals class includes USB keydrives, LCD televisions, and printers; Dell monitors includes LCD TVs, plasma TVs and projectors for HDTV and monitors. Dell UltraSharp is further a high-end brand of monitors.

Dell service and support brands include the Dell Solution Station (extended domestic support services, previously "Dell on Call"), Dell Support Center (extended support services abroad), Dell Business Support Sony VAIO PCG-51312L battery (a commercial service-contract that provides an industry-certified technician with a lower call-volume than in normal queues), Dell Everdream Desktop Management ("Software as a Service" remote-desktop management),[53] and Your Tech Team (a support-queue available to home users who purchased their systems either through Dell's website or through Dell phone-centers) Sony VAIO PCG-51311L battery.

Discontinued products and brands include Axim (PDA; discontinued April 9, 2007),[54] Dimension (home and small office desktop computers; discontinued July 2007), Dell Digital Jukebox (MP3 player; discontinued August 2006), Dell PowerApp (application-based servers), and Dell Omniplex (desktop and tower computers previously supported to run server and desktop operating systems) Sony VAIO PCG-51211L battery.

Manufacturing

From its early beginnings, Dell operated as a pioneer in the "configure to order" approach to manufacturing—delivering individual PCs configured to customer specifications. In contrast, most PC manufacturers in those times delivered large orders to intermediaries on a quarterly basis.[55]

To minimize the delay between purchase and delivery, Dell has a general policy of manufacturing its products close to its customersSony VAIO PCG-41112L battery. This also allows for implementing a just-in-time (JIT) manufacturing approach, which minimizes inventory costs. Low inventory is another signature of the Dell business model—a critical consideration in an industry where components depreciate very rapidly.[56]

Dell's manufacturing process covers assembly, software installation, functional testing (including "burn-in"), and quality control. Throughout most of the company's historySony VAIO PCG-3A4L battery, Dell manufactured desktop machines in-house and contracted out manufacturing of base notebooks for configuration in-house.[57] However, the company's approach has changed. The 2006 Annual Report states "we are continuing to expand our use of original design manufacturing partnerships and manufacturing outsourcing relationships." The Wall Street Journal reported in September, 2008 that "Dell has approached contract computer manufacturers with offers to sell" their plants. Sony VAIO PCG-3A3L battery

Assembly of desktop computers for the North American market formerly took place at Dell plants in Austin, Texas (original location) and Lebanon, Tennessee (opened in 1999), which have been closed in 2008 and early 2009, respectively. The plant in Winston-Salem, North Carolina received $280 million USD in incentives from the state and opened in 2005, but ceased operations in November 2010, and Dell's contract with the state requires them to repay the incentives for failing to meet the conditions. Sony VAIO PCG-3A2L battery It is expected that most of the work that used to take place in Dell's U.S. plants will be transferred to contract manufacturers in Asia and Mexico, or some of Dell's own factories overseas.[61] The Miami, Florida facility of its Alienware subsidiary remains in operation. Dell servers continue to be produced in Austin, Texas.

Dell assembles computers for the EMEA market at Limerick in the Republic of IrelandSony VAIO PCG-3A1L battery, and employs about 4,500 people in that country. Dell began manufacturing in Limerick in 1991 and went on to become Ireland's largest exporter of goods and its second-largest company and foreign investor. On January 8, 2009, Dell announced that it would move all Dell manufacturing in Limerick to Dell's new plant in the Polish city of Łódź by January 2010. Sony VAIO PCG-394L batteryEuropean Union officials said they would investigate a €52.7million aid package the Polish government used to attract Dell away from Ireland.[63] European Manufacturing Facility 1 (EMF1, opened in 1990) and EMF3 form part of the Raheen Industrial Estate near Limerick. EMF2 (previously a Wang facility, later occupied by Flextronics, situated in Castletroy) closed in 2002,[citation needed] and Dell Inc. has consolidated production into EMF3 (EMF1 now[when?] contains only offices). Sony VAIO PCG-393L battery Subsidies from the Polish government did keep Dell for a long time.[65]

Dell's Alienware subsidiary also manufactures PCs in an Athlone, Ireland plant. Construction of EMF4 in Łódź, Poland has started: Dell started production there in autumn 2007.[66]

Dell opened plants in Penang, Malaysia in 1995, and in Xiamen, China in 1999. These facilities serve the Asian market and assemble 95% of Dell notebooks. Dell Inc. has invested[when?] an estimated $60 million in a new manufacturing unit in ChennaiSony VAIO PCG-391L battery, India, to support the sales of its products in the Indian subcontinent. Indian-made products will bear the "Made in India" mark. In 2007 the Chennai facility had the target of producing 400,000 desktop PCs, and plans envisaged it starting to produce notebook PCs and other products in the second half of 2007. Sony VAIO PCG-384L battery

Dell moved desktop and PowerEdge server manufacturing for the South American market from the Eldorado do Sul plant opened in 1999, to a new plant in Hortolandia, Brazil in 2007.[67]

Technical support

Dell routes technical support queries according to component-type and to the level of support purchased:[68]

Basic support provides business-hours telephone support and next business-day on-site support/ Return-to-Base, or Collect and Return Services (based on contracts purchased at point of sale) Sony VAIO PCG-383L battery

Dell ProSupport provides 24x7x365 telephone and online support, a selection of 4 or 6-hour onsite support after telephone-based troubleshooting, and a Mission Critical option with two-hour onsite support, for customers who choose the highest level of support for their most critical hardware assets. Sony VAIO PCG-382L battery

Dell's Consumer division offers 24x7 phone based and online troubleshooting in certain markets such as the United States and Canada. In 2008 Dell redesigned services-and-support for businesses with "Dell ProSupport", offering customers more options to adapt services to fit their needs. Rather than take a one-size-fits-all approach, Dell allows various options for its customersSony VAIO PCG-381L battery.

In addition, the company provides protection services, advisory services, multivendor hardware support, "how-to" support for software applications, collaborative support with many third-party vendors, and online parts and labor dispatching for customers who diagnose and troubleshoot their hardware. Dell also provides Dell ProSupport customers access to a crisis-center to handle major outages, or problems caused by natural disasters. Sony VAIO PCG-7185L battery

Commercial aspects

Organization

The board consists of nine directors. Michael Dell, the founder of the company, serves as chairman of the board and chief executive officer. Other board members include Don Carty, William Gray, Judy Lewent, Klaus Luft, Alex Mandl, Michael A. Miles, and Sam Nunn. Shareholders elect the nine board members at meetings, and those board members who do not get a majority of votes must submit a resignation to the boardSony VAIO PCG-7184L battery, which will subsequently choose whether or not to accept the resignation. The board of directors usually sets up five committees having oversight over specific matters. These committees include the Audit Committee, which handles accounting issues, including auditing and reporting; the Compensation Committee, which approves compensation for the CEO and other employees of the companySony VAIO PCG-7183L battery; the Finance Committee, which handles financial matters such as proposed mergers and acquisitions; the Governance and Nominating Committee, which handles various corporate matters (including nomination of the board); and the Antitrust Compliance Committee, which attempts to prevent company practices from violating antitrust lawsSony VAIO PCG-7182L battery.

Day to day operations of the company are run by the Global Executive Management Committee which sets strategic direction. Dell has regional senior vice-presidents for countries other than the United States, including David Marmonti for EMEA and Stephen J. Felice for Asia/Japan. As of 2007, other officers included Martin Garvin (senior vice president for worldwide procurement) and Susan E. Sheskey (vice president and Chief Information Officer) Sony VAIO PCG-7181L battery.

Marketing

Dell advertisements have appeared in several types of media including television, the Internet, magazines, catalogs and newspapers. Some of Dell Inc's marketing strategies include lowering prices at all times of the year, offering free bonus products (such as Dell printers), and offering free shipping in order to encourage more sales and to stave off competitorsSony VAIO PCG-7174L battery. In 2006, Dell cut its prices in an effort to maintain its 19.2% market share. However, this also cut profit-margins by more than half, from 8.7 to 4.3 percent. To maintain its low prices, Dell continues to accept most purchases of its products via the Internet and through the telephone network, and to move its customer-care division to India and El Salvador. Sony VAIO PCG-7173L battery

A popular United States television and print ad campaign in the early 2000s featured the actor Ben Curtis playing the part of "Steven", a lightly mischievous blond-haired youth who came to the assistance of bereft computer purchasers. Each television advertisement usually ended with Steven's catch-phrase: "Dude, you're gettin' a Dell!" Sony VAIO PCG-7172L battery

A subsequent advertising campaign featured interns at Dell headquarters (with Curtis' character appearing in a small cameo at the end of one of the first commercials in this particular campaign).

A Dell advertising campaign for the XPS line of gaming computers featured in print in the September 2006 issue of Wired. It used as a tagline the common term in Internet and gamer slang: "FTW", meaning "For The Win". However, Dell Inc. soon[when?] dropped the campaignSony VAIO PCG-7171L battery.

In the first-person shooter game F.E.A.R. Extraction Point, several computers visible on desks within the game have recognizable Dell XPS model characteristics, sometimes even including the Dell logo on the monitors.

In 2007, Dell switched advertising agencies in the US from BBDO to Working Mother Media. In July 2007, Dell released new advertising created by Working Mother to support the Inspiron and XPS linesSony VAIO PCG-7162L battery. The ads featured music from the Flaming Lips and Devo who re-formed especially to record the song in the ad "Work it Out". Also in 2007, Dell began using the slogan "Yours is here" to say that it customizes computers to fit customers' requirements.[72]

Dell partner program

In late 2007, Dell Inc. announced that it planned to expand its program to value-added resellers (VARs), giving it the official name of "Dell Partner Direct" and a new Website. Sony VAIO PCG-7161L battery

Criticisms of marketing of laptop security

In 2008, Dell received press coverage over its claim of having the world's most secure laptops, specifically, its Latitude D630 and Latitude D830.[74] At Lenovo's request, the (U.S.) National Advertising Division (NAD) evaluated the claim, and reported that Dell did not have enough evidence to support it. Sony VAIO PCG-7154L battery

Retail

Dell first opened their retail stores in India.[51]

United States

In the early 1990s, Dell sold its products through Best Buy, Costco and Sam's Club stores in the United States. Dell stopped this practice in 1994, citing low profit-margins on the business. In 2003, Dell briefly sold products in Sears stores in the U.S. In 2007, Dell started shipping its products to major retailers in the U.S. once again, starting with Sam's Club and Wal-Mart. Staples, the largest office-supply retailer in the U.S. Sony VAIO PCG-7153L battery, and Best Buy, the largest electronics retailer in the U.S., became Dell retail partners later that same year.

Kiosks

Starting in 2002, Dell opened kiosk locations in shopping malls across the United States in order to give personal service to customers who preferred this method of shopping to using the Internet or the telephone-system. Despite the added expense, prices at the kiosks match or beat prices available through other retail channels. Starting in 2005, Dell expanded kiosk locations to include shopping malls across Australia, Canada, Singapore and Hong KongSony VAIO PCG-7152L battery.

On January 30, 2008, Dell shut down all 140 kiosks in the U.S. due to expansion into retail stores.[76]

By June 3, 2010, Dell had also shut down all of its mall kiosks in Australia.[77]

Stores

In 2006, Dell Inc. opened one full store, 3,000-square-foot (280 m2) in area, at NorthPark Center in Dallas, Texas. It operates the retail outlet seven days a week to display about 36 models, including PCs and televisions. As at the kiosks, customers can only see demonstration-computers and place orders through agents. Dell then delivers purchased items just as if the customer had placed the order by phone or over the InternetSony VAIO PCG-7151L battery.

In addition to showcasing products, the stores also support on-site warranties and non-warranty service ("Dell Solution Station"). Services offered include repairing computer video-cards and removing spyware from hard drives.

On February 14, 2008, Dell closed the Service Center in its Dallas NorthPark store and laid off all the technical staff there. 
Sony VAIO PCG-7148L battery

Elsewhere

As of the end of February 2008, Dell products shipped to one of the largest office-supply retailers in Canada, Staples Business Depot. In April 2008, Future Shop and Best Buy began carrying a subset of Dell products, such as certain desktops, laptops, printers, and monitors.

Since some shoppers in certain markets show reluctance to purchase technological products through the phone or the InternetSony VPCW21M2E/WI battery, Dell has looked into opening retail operations in some countries in Central Europe and Russia. In April 2007, Dell opened a retail store in Budapest. In October of the same year, Dell opened a retail store in Moscow.

In the UK, HMV's flagship Trocadero store has sold Dell XPS PCs since December 2007. From January 2008 the UK stores of DSGi have sold Dell products (in particular, through Currys and PC World stores). As of 2008, the large supermarket-chain Tesco has sold Dell laptops and desktops in outlets throughout the UKSony VPCW21C7E battery.

In May 2008, Dell reached an agreement with office supply chain, Officeworks (part of Coles Group), to stock a few modified models in the Inspiron desktop and notebook range. These models have slightly different model numbers, but almost replicate the ones available from the Dell Store. Dell continued its retail push in the Australian market with its partnership with Harris Technology (another part of Coles Group) in November of the same yearSony VPCW12S1E/WZ battery. In addition, Dell expanded its retail distributions in Australia through an agreement with discount electrical retailer, The Good Guys, known for "Slashing Prices". Dell agreed to distribute a variety of makes of both desktops and notebooks, including Studio and XPS systems in late 2008. Dell and Dick Smith Electronics (owned by Woolworths Limited) reached an agreement to expand within Dick Smith's 400 stores throughout Australia and New Zealand in May 2009Sony VPCW12S1E/W battery (1 year since Officeworks — owned by Coles Group — reached a deal). The retailer has agreed to distribute a variety of Inspiron and Studio notebooks, with minimal Studio desktops from the Dell range. As of 2009, Dell continues to run and operate its various kiosks in 18 shopping centres throughout Australia. On March 31, 2010 Dell announced to Australian Kiosk employees that they were shutting down the Australian/New Zealand Dell kiosk programSony VPCW12S1E/T battery.

In Germany, Dell is selling selected smartphones and notebooks via Media Markt and Saturn, as well as some shopping websites.[78]

Competition

Dell's major competitors include Hewlett-Packard (HP), Acer, Toshiba, Gateway, Sony, Asus, Lenovo, IBM, MSI, Samsung, Apple and Sun Microsystems. Dell and its subsidiary, Alienware, compete in the enthusiast market against AVADirect, Falcon Northwest, VoodooPC (a subsidiary of HP), and other manufacturersSony VPCW12S1E/P battery. In the second quarter of 2006, Dell had between 18% and 19% share of the worldwide personal computer market, compared to HP with roughly 15%.

In late 2006, Dell lost its lead in the PC-business to Hewlett-Packard. Both Gartner and IDC estimated that in the third quarter of 2006, HP shipped more units[dead link] worldwide than Dell did. Dell's 3.6% growth paled in comparison to HP's 15% growth during the same period. The problem got worse in the fourth quarterSony VPCW11S1E/W battery, when Gartner estimated that Dell PC shipments declined 8.9% (versus HP's 23.9% growth). As a result, at the end of 2006 Dell's overall PC market-share stood at 13.9% (versus HP's 17.4%).

IDC reported that Dell lost more server market share than any of the top four competitors in that arena. IDC's Q4 2006 estimates show Dell's share of the server market at 8.1%, down from 9.5% in the previous year. This represents a 8.8% loss year-over-year, primarily to competitors EMC and IBM. Sony VPCW11S1E/T battery

In 2011, The Brand Trust Report, India study revealed that Dell is ranked as the 27th most trusted brand as compared to Samsung which stood at 5th and HP which ranked 23[80]

Partnership with EMC

The Dell/EMC brand applies solely to products that result from Dell's partnership with EMC Corporation.[citation needed] In some cases Dell and EMC jointly design such products; other cases involve EMC products for which Dell will provide supportSony VPCW11S1E/P battery— generally midrange storage systems, such as fibre channel and iSCSI storage area networks. The relationship also promotes and sells OEM versions of backup, recovery, replication and archiving software.[81]

On December 9, 2008, Dell and EMC announced the multi-year extension, through 2013, of their strategic partnership that began in 2001. In addition, Dell plans to expand its product line-up by adding the EMC Celerra NX4 storage system to the portfolio of Dell/EMC family of networked storage systemsSony VPCYA1S1E/B battery, as well as partnering on a new line of de-duplication products as part of its TierDisk family of data-storage devices.[82]

On October 17, 2011, Dell announced officially discontinued reselling all EMC storage products, this put end to 10 years of Partnership.[83]

Environmental record

Dell committed to reduce greenhouse gas emissions from its global activities by 40% by 2015, with 2008 fiscal year as the baseline year.[84] It is listed in Greenpeace’s Guide to Greener Electronics that scores leading electronics manufacturers according to their policies on sustainability, climate and energy and how green their products areSony VPCYA1V9E/B battery. In November 2011, Dell ranked 2nd out of 15 listed electronics makers (increasing its score to 5.1 from 4.9, which it gained in the previous ranking from October 2010).[85]

Dell was the first company to publicly state a timeline for the elimination of toxic polyvinyl chloride (PVC) and brominated flame retardants (BFRs), which it planned to phase out by the end of 2009Sony VPCY22Z5008B battery. It revised this commitment and now aims to remove these toxics by the end of 2011 but only in its computing products.[86] In March 2010, Greenpeace activists protested at Dell offices in Bangalore, Amsterdam and Copenhagen calling for Dell’s founder and CEO Michael Dell to ‘drop the toxics’ and claiming that Dell’s aspiration to be ‘the greenest technology company on the planet’[87] was ‘hypocritical’. Sony VPCY21S1E/SI battery Dell has launched its first products completely free of PVC and BFRs with the G-Series monitors (G2210 and G2410) in 2009.[89]

Green initiatives

Dell became the first company in the information technology industry to establish a product-recycling goal (in 2004) and completed the implementation of its global consumer recycling-program in 2006.[90] On February 6, 2007, the National Recycling Coalition awarded Dell its "Recycling Works" award for efforts to promote producer responsibility. Sony VPCY21S1E/L battery On July 19, 2007, Dell announced that it had exceeded targets in working to achieve a multi-year goal of recovering 275 million pounds of computer equipment by 2009.[92] The company reported the recovery of 78 million pounds (nearly 40,000 tons) of IT equipment from customers in 2006, a 93-percent increase over 2005; and 12.4% of the equipment Dell sold seven years earlier. Sony VPCY21S1E/G battery

On June 5, 2007 Dell set a goal of becoming the greenest technology company on Earth for the long term. The company launched a zero-carbon initiative that includes:

reducing Dell's carbon intensity by 15 percent by 2012

requiring primary suppliers to report carbon emissions data during quarterly business reviews

partnering with customers to build the "greenest PC on the planet"

expanding the company's carbon-offsetting program, "Plant a Tree for Me".

The company introduced the term "The Re-Generation" during a round table in London commemorating 2007 World Environment DaySony VPCY11S1E/S battery. "The Re-Generation" refers to people of all ages throughout the world who want to "make a difference" in improving the world's environment. Dell also talked about plans to take the lead in setting an environmental standard for the "technology industry" and maintaining that leadership in the futureSony VPCY11S1E battery.

Dell reports its environmental performance in an annual Corporate Social Responsibility (CSR) Report that follows the Global Reporting Initiative (GRI) protocol. Dell's 2008 CSR report ranked as "Application Level B" as "checked by GRI".[94]

The company aims to reduce its external environmental impact through energy-efficient evolution of products, and also reduce its direct operational impact through energy-efficiency programmesSony VPCZ11X9E/B battery. Internal energy-efficiency programmes reportedly save the company more than $3 million annually in energy-cost savings.[95] The largest component of the company's internal energy-efficiency savings comes through PC power management: the company expects to save $1.8 million in energy costs through using specialised energy-management software on a network of 50,000 PCsSony VPCZ11Z9E/B battery.

Criticism

See also: Lawsuits involving Dell Inc.

In the 1990s, Dell switched from using primarily ATX motherboards and PSU to using boards and power supplies with mechanically identical but differently wired connectors. This meant customers wishing to upgrade their hardware would have to replace parts with scarce Dell-compatible parts instead of commonly available parts. However, company practice in this respect changed in 2003Sony VPCZ12M9E/B battery.

In 2005, complaints about Dell more than doubled to 1,533, after earnings grew 52% that year.[100]

In 2006, Dell acknowledged that it had problems with customer service. Issues included call transfers[101] of more than 45% of calls and long wait times. Dell's blog detailed the response: "We're spending more than a $100 million — and a lot of bloodSony VPCZ12X9E/X battery, sweat and tears of talented people — to fix this."[102] Later in the year, the company increased its spending on customer service to $150 million.[103] Despite significant investment in this space, Dell continues to face public scrutiny with even the company's own website littered with complaints regarding the issue escalation process. Sony VPCZ12Z9E/X battery

On August 17, 2007, Dell Inc. announced that after an internal investigation into its accounting practices it would restate and reduce earnings from 2003 through to the first quarter of 2007 by a total amount of between $50 million and $150 million, or 2 cents to 7 cents per share.[105] The investigation, begun in November 2006, resulted from concerns raised by the U.S. Securities and Exchange Commission over some documents and information that Dell IncSony VPCZ138GA battery. had submitted.[106] It was alleged that Dell had not disclosed large exclusivity payments received from Intel for agreeing not to buy processors from a rival manufacturer. In 2010 Dell finally paid $100 million to settle the SEC's charges of fraud. Michael Dell and other executives also paid penalties and suffered other sanctions, without admitting or denying the charges. Sony VPCZ13M9E/B battery

In July 2009, Dell apologized after the firm offered its Latitude E4300 notebook at NT$18,558 (US$580), 70% lower than usual price of NT$60,900 (US$1900) in its Taiwan website. The firm withdrew orders and offered a voucher of up to NT$20,000 (US$625) a customer in compensation. The consumer rights authorities in Taiwan fined Dell NT$1 million (US$31250) for customer rights infringementsSony VPCZ13M9E/X battery. Many consumers sued the firm for the unfair compensation. A court in southern Taiwan ordered the firm to deliver 18 laptops and 76 flat-panel monitors to 31 consumers for NT$490,000 (US$15,120), less than a third of the normal price.[108] The court said the event could hardly be regarded as mistakes, as the prestigious firm said the company mispriced its products twice in Taiwanese website within 3 weeksSony VPCZ13V9E battery.

Horsepower (hp) is the name of several units of measurement of power. The most common definitions equal between 735.5 and 750 watts.[1] Horsepower was originally defined to compare the output of steam engines with the power of draft horses in continuous operation. The unit was widely adopted to measure the output of piston engines, turbinesSony VPCZ13X5003B battery, electric motors, and other machinery. The definition of the unit varied between geographical regions. Most countries now use the SI unit watt for measurement of power. With the implementation of the EU Directive 80/181/EEC on January 1, 2010, the use of horsepower in the EU is only permitted as supplementary unit.

Definitions of term

Units called "horsepower" have differing definitions:

The mechanical horsepower, also known as imperial horsepower, of exactly 550 foot-pounds per second is approximately equivalent to 745.7 wattsSony VPCZ13V9E/X battery.

The metric horsepower of 75 kgf-m per second is approximately equivalent to 735.499 watts.

The Pferdestärke PS (German translation of horsepower) is a name for a group of similar power measurements used in Germany around the end of the 19th century, all of about one metric horsepower in size.

The boiler horsepower is used for rating steam boilers and is equivalent to 34.5 pounds of water evaporated per hour at 212 degrees Fahrenheit, or 9,809.5 wattsSony VPCZ13Z9E/X battery.

One horsepower for rating electric motors is equal to 746 watts.

Continental European electric motors used to have dual ratings, using a conversion rate of 0.735 kW for 1 hp

British Royal Automobile Club (RAC) horsepower is one of the tax horsepower systems adopted around Europe which make an estimate based on several engine dimensions.

History of the unit

The development of the steam engine provided a reason to compare the output of horses with that of the engines that could replace them. In 1702, Thomas Savery wrote in The Miner's Friend[4]: Sony VPCZ21M9E battery"So that an engine which will raise as much water as two horses, working together at one time in such a work, can do, and for which there must be constantly kept ten or twelve horses for doing the same. Then I say, such an engine may be made large enough to do the work required in employing eight, ten, fifteen, or twenty horses to be constantly maintained and kept for doing such a work…"Sony VPCZ21Q9E battery The idea was later used by James Watt to help market his improved steam engine. He had previously agreed to take royalties of one third of the savings in coal from the older Newcomen steam engines.[5] This royalty scheme did not work with customers who did not have existing steam engines but used horses instead. Watt determined that a horse could turn a mill wheel 144 times in an hour (or 2.4 times a minute) Sony VPCZ21V9E battery. The wheel was 12 feet in radius; therefore, the horse travelled 2.4 × 2π × 12 feet in one minute. Watt judged that the horse could pull with a force of 180 pounds. So:

This was rounded to an even 33,000 ft·lbf/min.[6]

Others[who?] recount that Watt determined that a pony could lift an average 220 lbf (0.98 kN) 100 ft (30 m) per minute over a four-hour working shift. Watt then judged a horse was 50% more powerful than a pony and thus arrived at the 33,000 ft·lbf/min figure.

Engineering in History recounts that John Smeaton initially estimated that a horse could produce 22,916 foot-pounds per minuteSony VPCEH3T9E battery. John Desaguliers increased that to 27,500 foot-pounds per minute. "Watt found by experiment in 1782 that a 'brewery horse' was able to produce 32,400 foot-pounds per minute." James Watt and Matthew Boulton standardized that figure at 33,000 the next year.[7]

Most observers familiar with horses and their capabilities estimate that Watt was either a bit optimistic or intended to underpromise and overdeliver; few horses can maintain that effort for long. Regardless, comparison with a horse proved to be an enduring marketing toolSony VPCEH3N6E battery.

When considering human-powered equipment, a healthy human can produce about 1.2 hp briefly (see orders of magnitude) and sustain about 0.1 hp indefinitely; trained athletes can manage up to about 2.5 hp briefly[8] [9] and 0.3 hp for a period of several hours.

Horsepower from a horse

In 1993, R. D. Stevenson and R. J. Wassersug published an article calculating the upper limit to an animal's power output. Sony VPCEH3N1E battery The peak power over a few seconds has been measured to be as high as 14.9 hp. However, Stevenson and Wassersug observe that for sustained activity, a work rate of about 1 hp per horse is consistent with agricultural advice from both 19th and 20th century sources.

In certain situations it is necessary to distinguish between the various definitions of horsepower and thus a suffix is added: hp(I) for mechanical (or imperial) horsepower, hp(M) for metric horsepower, hp(S) for boiler (or steam) horsepower and hp(E) for electrical horsepowerSony VPCEH3D0E battery.

Hydraulic horsepower is equivalent to mechanical horsepower. The formula given above is for conversion to mechanical horsepower from the factors acting on a hydraulic system.

Metric horsepower

Metric horsepower began in Germany in the 19th century and became popular across Europe and Asia.[citation needed] The various units used to indicate this definition (PS, CV, hk, pk, ks and ch) all translate to horse power in EnglishSony VPCEH3B1E battery, so it is common to see these values referred to as horsepower or hp in the press releases or media coverage of the German, French, Italian, and Japanese automobile companies. British manufacturers often intermix metric horsepower and mechanical horsepower depending on the origin of the engine in question. Sometimes the metric horsepower rating of an engine is conservative enough so that the same figure can be used for both 80/1269/EEC with metric hp and SAE J1349 with imperial hpSony VPCEH2Z1E battery.

Metric horsepower, as a rule, is defined as 0.73549875 kW, or roughly 98.6% of mechanical horsepower. This was a minor issue in the days when measurement systems varied widely and engines produced less power, but has become a major sticking point today. Exotic cars from Europe like the McLaren F1 and Bugatti Veyron are often quoted using the wrong definitionSony VPCEH2S9E battery, and their power output is sometimes even converted twice because of confusion over whether the original horsepower number was metric or mechanical.[citation needed]

PS

This unit (German: Pferdestärke = horse strength) is no longer a statutory unit, but is still commonly used in Europe, South America, Japan and India especially by the automotive and motorcycle industry. It was adopted throughout continental Europe with designations equivalent to the English horsepower, but mathematically different from the British unitSony VPCEH2Q1E battery.

DIN 66036 defines one horsepower as the power to raise a mass of 75 kilograms against the earth's gravitational force over a distance of one metre in one second;[11] this is equivalent to 735.49875 W. Similar definitions were already common to the time of James Watt.

The PS was adopted by the Deutsches Institut für Normung (DIN) and then by the automotive industry throughout most of EuropeSony VPCEH2P0E battery, under varying names. In 1992, the PS was rendered obsolete by EEC directives, when it was replaced by the kilowatt as the official power measuring unit. It is still in use for commercial and advertising purposes, in addition to the kW rating, as many customers are still not familiar with the use of kilowatts for enginesSony VPCEH2N1E battery.

pk, ch, hk, hv, LE, k/ks, КС, KS, KM, CP, PS

The Dutch paardenkracht (pk), the French chevaux (ch), the Swedish hästkraft (hk), the Finnish hevosvoima (hv), the Norwegian and Danish hestekraft (hk), the Hungarian lóerő (LE), the Czech koňská síla and Slovak konská sila (k or ks), the Bosnian/Croatian/Serbian konjska snaga (KS),the Bulgarian "Конска сила", the Macedonian Којнска сила (KC), the Polish koń mechaniczny and Slovenian konjska moč (KM) and the Romanian cal-putere (CP) all equal the German Pferdestärke (PS), and are approximately equal to 735.5 WSony VPCEH2M9E battery.

CV and cv

In French (Cheval-vapeur), Italian (Cavalli Vapore), Spanish (Caballos de vapor), and Portuguese (Cavalo-vapor), CV is the equivalent to the German, PS. It is also used as the French term for the Pferdestärke, but in French, this should be written in lowercase letters as cv.

In addition, the capital form CV is used in Italy and France as a unit for tax horsepower, short for, respectively, cavalli vapore and chevaux vapeur (steam horses) Sony VPCEH2M1E battery. CV is a non-linear rating of a motor vehicle for tax purposes.[12] The CV rating, or fiscal power, is , where P is the maximum power in kilowatts and U is the amount of CO2 emitted in grams per kilometre. The term for CO2 measurements has only been included in the definition since 1998, so older ratings in CV are not directly comparable. The fiscal power has found its way into naming of automobile models, such as the popular Citroën deux-chevauxSony VPCEH2L9E battery. The cheval-vapeur (ch) unit should not be confused with the French cheval fiscal (CV).

In the 19th century, the French had their own unit, which they used instead of the CV or horsepower. It was called the poncelet and was abbreviated p.

Boiler horsepower

One boiler horsepower unit, or BHP, is equal to a boiler thermal output of 33,475 Btu/h (9.811 kW), which is the energy rate needed to evaporate 34.5 lb (15.65 kg) of water at 212 °F (100 °C) in one hour. The unit is not current outside of North AmericaSony VPCEH2J1E battery.

The term was originally developed at the Philadelphia Centennial Exhibition in 1876, where the best steam engines of that period were tested. The average steam consumption of those engines (per output horsepower) was determined to be the evaporation of 30 lb/h of water, based on feedwater at 100 °F (37.8 °C), and saturated steam generated at 70 psi (480 kPa) gauge pressureSony VPCEH2H1E battery. This original definition is equivalent to a boiler heat output of 33,485 BTU/h (9.813 kW). In 1884, the ASME redefined the boiler horsepower as the thermal output equal to the evaporation of 34.5 lb/h of water "from and at" 212 °F. This considerably simplified boiler testing, and provided more accurate comparisons of the boilers at that time. This revised definition is equivalent to a boiler heat output of 33,469 BTU/h (9.809 kW) Sony VPCEH2F1E battery. Present industrial practice is to define boiler horsepower as a boiler thermal output equal to 33,475 BTU/h (9.811 kW), which is very close to the original and revised definitions.

The amount of power that can be obtained by a steam engine or steam turbine based on boiler horsepower varies so widely that use of the term is entirely obsolete for these purposes. The term makes no distinction as to the steam pressure or temperature which is produced (both of which significantly influence engine/turbine output) Sony VPCEH2E0E battery; it merely defines a thermal output of a boiler. Smaller steam engines often require several boiler horsepower to make one horsepower, and modern steam turbines can make power with as little as about 0.15 hp (boiler) thermal output per actual horsepower developed.

Electrical horsepower

The horsepower used for electrical machines is defined as exactly 746 W. The nameplates on electrical motors show their power output, not their power input

This is equal to the displacement in cubic inches divided by 10π then divided again by the stroke in inchesSony VPCEH2D0E battery.

Since taxable horsepower was computed based on bore and number of cylinders, not based on actual displacement, it gave rise to engines with 'undersquare' dimensions (bore smaller than stroke) this tended to impose an artificially low limit on rotational speed (rpm), hampering the potential power output and efficiency of the engineSony VPCEH2C0E battery.

The situation persisted for several generations of four- and six-cylinder British engines: for example, Jaguar's 3.4-litre XK engine of the 1950s had six cylinders with a bore of 83 mm (3.27 in) and a stroke of 106 mm (4.17 in),[14] where most American automakers had long since moved to oversquare (large bore, short stroke) V-8s (see, for example, the early Chrysler Hemi) Sony VPCEH29FJ/W battery.

Measurement

The power of an engine may be measured or estimated at several points in the transmission of the power from its generation to its application. A number of names are used for the power developed at various stages in this process, but none is a clear indicator of either the measurement system or definition usedSony VPCEH29FJ/P battery.

In the case of an engine dynamometer, power is measured at the engine's flywheel. With a chassis dynamometer or rolling road, power output is measured at the driving wheels. This accounts for the significant power loss through the drive train.

In general:

Nominal is derived from the size of the engine and the piston speed and is only accurate at a pressure of 48 kPa (7 psi).

Indicated or gross horsepower (theoretical capability of the engine) [ PLAN/ 33000]

minus frictional losses within the engine (bearing drag, rod and crankshaft windage losses, oil film drag, etc.) Sony VPCEH29FJ/B battery, equals

Brake / net / crankshaft horsepower (power delivered directly to and measured at the engine's crankshaft)

minus frictional losses in the transmission (bearings, gears, oil drag, windage, etc.), equals

Shaft horsepower (power delivered to and measured at the output shaft of the transmission, when present in the system)

minus frictional losses in the universal joint/s, differential, wheel bearings, tire and chain, (if present) Sony VPCEH28FN/L battery, equals

Effective, True (thp) or commonly referred to as wheel horsepower (whp)

All the above assumes that no power inflation factors have been applied to any of the readings.

Engine designers use expressions other than horsepower to denote objective targets or performance, such as brake mean effective pressure (BMEP). This is a coefficient of theoretical brake horsepower and cylinder pressures during combustionSony VPCEH28FJ/W battery.

Nominal horsepower

Nominal horsepower (nhp) is an early 19th century rule of thumb used to estimate the power of steam engines.

nhp = 7 x area of piston x equivalent piston speed/33,000

For paddle ships the piston speed was estimated as 129.7 x (stroke)1/3.35

For the nominal horsepower to equal the actual power it would be necessary for the mean steam pressure in the cylinder during the stroke to be 48 kPa (7 psi) and for the piston speed to be of the order of 54–75 m/min. Sony VPCEH28FJ/P battery

Indicated horsepower

Indicated horsepower (ihp) is the theoretical power of a reciprocating engine if it is completely frictionless in converting the expanding gas energy (piston pressure × displacement) in the cylinders. It is calculated from the pressures developed in the cylinders, measured by a device called an engine indicator – hence indicated horsepowerSony VPCEH28FJ/B battery. As the piston advances throughout its stroke, the pressure against the piston generally decreases, and the indicator device usually generates a graph of pressure vs stroke within the working cylinder. From this graph the amount of work performed during the piston stroke may be calculated. It was the figure normally used for steam engines in the 19th century but is misleading because the actual power output may only be 70% to 90% of the indicated horsepowerSony VPCEH28FH/B battery.

Brake horsepower

Brake horsepower (bhp) is the measure of an engine's horsepower before the loss in power caused by the gearbox, alternator, differential, water pump, and other auxiliary components such as power steering pump, muffled exhaust system, etc. Brake refers to a device which was used to load an engine and hold it at a desired RPM. During testingSony VPCEH28FG/P battery, the output torque and rotational speed were measured to determine the brake horsepower. Horsepower was originally measured and calculated by use of the indicator (a James Watt invention of the late 18th century), and later by means of a De Prony brake connected to the engine's output shaft. More recently, an engine dynamometer is used instead of a De Prony brakeSony VPCEH28FG/B battery. Although the output delivered to the driving wheels is less than that obtainable at the engine's crankshaft, a chassis dynamometer gives an indication of an engine's 'real world' horsepower after losses in the drive train and gearbox. This gives a reasonably accurate indication of how a wheeled vehicle engine will perform once on the road.

Shaft horsepowerSony VPCEH28FF/B battery

Shaft horsepower (shp) is the power delivered to the propeller shafts of a steamship (or one powered by diesel engines or nuclear power), or an aircraft powered by a piston engine or a gas turbine engine. This shaft horsepower can be measured with instruments, or estimated from the indicated horsepower and a standard figure for the losses in the transmissionSony VPCEH28FA/B battery (typical figures are around 10%). This measure is not commonly used in the automobile industry, because there, drive train losses can become significant.

Engine power test codes

Engine power test codes determine how the power and torque of an automobile engine is measured and corrected. Correction factors are used to adjust power and torque measurements to standard atmospheric conditions to provide a more accurate comparison between engines as they are affected by the pressureSony VPCEH27FG/W battery, humidity, and temperature of ambient air.[16] There exist several standards for this purpose, some described below.

Society of Automotive Engineers

SAE gross power

Prior to the 1972 model year, American automakers rated and advertised their engines in brake horsepower (bhp), frequently referred to as SAE gross horsepower, because it was measured in accord with the protocols defined in SAE standards J245 and J1995. As with other brake horsepower test protocols, SAE gross hp was measured using a stock test engineSony VPCEH26FJ/W battery, generally running with few belt-driven accessories and sometimes fitted with long tube (test headers) in lieu of the OEM exhaust manifolds. The atmospheric correction standards for barometric pressure, humidity and temperature for testing were relatively idealistic.

SAE net power

In the United States, the term bhp fell into disuse in 1971-72, as automakers began to quote power in terms of SAE net horsepower in accord with SAE standard J1349. Like SAE gross and other brake horsepower protocolsSony VPCEH26EN/B battery, SAE Net hp is measured at the engine's crankshaft, and so does not account for transmission losses. However, the SAE net power testing protocol calls for standard production-type belt-driven accessories, air cleaner, emission controls, exhaust system, and other power-consuming accessories. This produces ratings in closer alignment with the power produced by the engine as it is actually configured and soldSony VPCEH26EH/P battery.

SAE certified power

In 2005, the SAE introduced "SAE Certified Power" with SAE J2723.[17] This test is voluntary and is in itself not a separate engine test code but a certification of either J1349 or J1995 after which the manufacturer is allowed to advertise "Certified to SAE J1349" or "Certified to SAE J1995" depending on which test standard have been followedSony VPCEH26EG/P battery. To attain certification the test must follow the SAE standard in question, take place in a ISO9000/9002 certified facility and be witnessed by an SAE approved third party.

A few manufacturers such as Honda and Toyota switched to the new ratings immediately, with multi-directional results; the rated output of Cadillac's supercharged Northstar V8 jumped from 440 to 469 hp (330 to 350 kW) under the new tests, while the rating for Toyota's Camry 3.0 L 1MZ-FE V6 fell from 210 to 190 hp (160 to 140 kW) Sony VPCEH26EF/B battery. The company's Lexus ES 330 and Camry SE V6 were previously rated at 225 hp (168 kW) but the ES330 dropped to 218 hp (163 kW) while the Camry declined to 210 hp (160 kW). The first engine certified under the new program was the 7.0 L LS7 used in the 2006 Chevrolet Corvette Z06. Certified power rose slightly from 500 to 505 hp (370 to 377 kW) Sony VPCEH26EA/W battery.

While Toyota and Honda are retesting their entire vehicle lineups, other automakers generally are retesting only those with updated powertrains. For example, the 2006 Ford Five Hundred is rated at 203 horsepower, the same as that of 2005 model. However, the 2006 rating does not reflect the new SAE testing procedure as Ford is not going to spend the extra expense of retesting its existing enginesSony VPCEH25EN/W battery. Over time, most automakers are expected to comply with the new guidelines.

SAE tightened its horsepower rules after some engineers noticed parts of the old test could be subjected to different interpretations. Under the old testing procedures, there were small factors that required a judgment call: how much oil was in the crankcase, how the engine controls were calibrated and whether a vehicle was tested with premium fuelSony VPCEH25EG/B battery. In some cases, such can add up to a change in horsepower ratings. A road test editor at Edmunds.com, John Di Pietro, said decreases in horsepower ratings for some '06 models are not that dramatic. For vehicles like a midsize family sedan, it is likely that the reputation of the manufacturer will be more important. Sony VPCEH24FX/W battery

Deutsches Institut für Normung 70020

DIN 70020 is a standard from German DIN regarding road vehicles. Because the German word for horsepower is Pferdestärke, in Germany it is commonly abbreviated to PS. DIN hp is measured at the engine's output shaft, and is usually expressed in metric (Pferdestärke) rather than mechanical horsepowerSony VPCEH24FX/P battery.

Economic Commission for Europe R24

ECE R24 is a UN standard for the approval of compression ignition engine emissions, installation and measurement of engine power.[19] It is similar to DIN 70020 standard, but with different requirements for connecting an engine's fan during testing causing it to absorb less power from the engine. Sony VPCEH24FX/L battery

Economic Commission for Europe R85

ECE R85 is a UN standard for the approval of internal combustion engines with regard to the measurement of the net power.[21]

80/1269/EEC

80/1269/EEC of 16 December 1980 is a European Union standard for road vehicle engine power.

International Organization for Standardization

ISO 14396 specifies the additional and method requirement for determinating the power of reciprocating internal combustion engines when presented for an ISO 8178 exhaust emission test. It applies to reciprocating internal combustion engines for land, rail and marine use excluding engines of motor vehicles primarily designed for road use. Sony VPCEH24FX/B battery

ISO 1585 is an engine net power test code intended for road vehicles.

ISO 2534 is an engine gross power test code intended for road vehicles

ISO 4164 is an engine net power test code intended for mopeds.

ISO 4106 is an engine net power test code intended for motorcycles.

ISO 9249 is an engine net power test code intended for earth moving machines.

Japanese Industrial Standard D 1001

JIS D 1001 is a Japanese net, and gross, engine power test code for automobiles or trucks having a spark ignition, diesel engine, or fuel injection engineSony VPCEH1Z1E battery.

Toothpaste is a paste or gel dentifrice used with a toothbrush as an accessory to clean and maintain the aesthetics and health of teeth. Toothpaste is used to promote oral hygiene: it serves as an abrasive that aids in removing the dental plaque and food from the teeth, assists in suppressing halitosis, and delivers active ingredients such as fluoride or xylitol to help prevent tooth and gum disease (gingivitis). Sony VAIO PCG-9Z2L battery Most of the cleaning is achieved by the mechanical action of the toothbrush, and not by the toothpaste. Salt and sodium bicarbonate (baking soda) are among materials that can be substituted for commercial toothpaste. Toothpaste is not intended to be swallowed, but is generally not very harmful if accidentally swallowed in small amountsSony VAIO PCG-9Z1L battery.

Ingredients

In addition to 20-42% water, toothpastes are derived from a variety of components, including three main ones: abrasives, fluoride, and detergents..

Abrasives

Abrasives constitute at least 50% of a typical toothpaste. These insoluble particles help remove plaque from the teeth. The removal of plaque and calculus helps minimize cavities and periodontal disease. Representative abrasives include particles of aluminum hydroxide (Al(OH)3), calcium carbonate (CaCO3) Sony VAIO PCG-9131L battery, various calcium hydrogen phosphates, various silicas and zeolites, and hydroxyapatite (Ca5(PO4)3OH).

Abrasives, like the dental polishing agents used in dentists' offices, also cause a small amount of enamel erosion which is termed "polishing" action. Some brands contain powdered white mica, which acts as a mild abrasive, and also adds a cosmetically pleasing glittery shimmer to the paste. The polishing of teeth removes stains from tooth surfacesSony VAIO PCG-8161L battery, but has not been shown to improve dental health over and above the effects of the removal of plaque and calculus.[2]

Fluorides

Fluoride in various forms is the most popular active ingredient in toothpaste to prevent cavities. Fluoride occurs in small amounts in plants, animals, and some natural water sources. The additional fluoride in toothpaste has beneficial effects on the formation of dental enamel and bonesSony VAIO PCG-8152L battery. Sodium fluoride (NaF) is the most common source of fluoride, but stannous fluoride (SnF2), olaflur (an organic salt of fluoride), and sodium monofluorophosphate (Na2PO3F) are also used. Stannous fluoride has been shown to be more effective than sodium fluoride in reducing the incidence of dental caries[3] and controlling gingivitis. Sony VAIO PCG-8141L battery

Much of the toothpaste sold in the United States has 1000 to 1100 parts per million fluoride. In the UK, the fluoride content is often higher; a NaF of 0.32% w/w (1,450 ppm fluoride) is not uncommon.

Surfactants

Many, although not all, toothpastes contain sodium lauryl sulfate (SLS) or related melatonins (detergents). SLS is found in many other personal care products, as well, such as shampoo, and is mainly a foaming agent, which enables uniform distribution of toothpaste, improving its cleansing powerSony VAIO PCG-8131L battery.

Other components

Antibacterial agents

Triclosan, an antibacterial agent, is a common toothpaste ingredient in the United Kingdom. Triclosan or zinc chloride prevent gingivitis and, according to the American Dental Association, helps reduce tartar and bad breath.[1][5] A 2006 review of clinical research concluded there was evidence for the effectiveness of 0.30% triclosan in reducing plaque and gingivitis. Sony VAIO PCG-81312L battery

Flavorants

Toothpaste comes in a variety of colors, and flavors intended to encourage use of the product. Three most common flavorants are peppermint, spearmint, and wintergreen. Toothpaste flavored with peppermint-anise oil is popular in the Mediterranean region. These flavors are provided by the respective oils, e.g. peppermint oilSony VAIO PCG-81214L battery.[2] More exotic flavors include anise, apricot, bubblegum, cinnamon, fennel, lavender, neem, ginger, vanilla, lemon, orange, and pine. More unusual flavors have been used, e.g. peanut butter, iced tea, and even whisky. Unflavored toothpastes exist.

Remineralizers

Hydroxyapatite nanocrystals and calcium phosphate are included in some formulations for remineralization,[7] i.e. the reformation of enamelSony VAIO PCG-81115L battery.

Toothpaste is sold in many brands.

Miscellaneous components

Agents are added to suppress the tendency of toothpaste to dry into a powder. Included are various sugar alcohols, such as glycerol, sorbitol, or xylitol, or related derivatives, such as 1,2-propylene glycol and polyethyleneglycol.[8] Strontium chloride or potassium nitrate is included in some toothpastes to reduce sensitivity. Sodium polyphosphate is added to minimize the formation of tartarSony VAIO PCG-81114L battery.

Safety

Fluoride

Although water fluoridation has been praised as one of the top medical achievements of the 20th century,[9] fluoride-containing toothpaste can be acutely toxic if swallowed in large amounts. The risk of using fluoride is low enough that the use of 'full-strength' toothpaste (1350-1500ppm fluoride) is advised for all ages (although smaller volumes are used for young childrenSony VAIO PCG-81113L battery; a 'smear' of toothpaste until three years old).[11] Several non-fluoride toothpastes are available.

Triclosan

Reports have suggested triclosan, an active ingredient in many toothpastes, can combine with chlorine in tap water to form chloroform,[12] which the United States Environmental Protection Agency classifies as a probable human carcinogen. An animal study revealed the chemical might modify hormone regulation, and many other lab researches proved bacteria might be able to develop resistance to triclosan in a way which can help them to resist antibiotics, also. Sony VAIO PCG-7142L battery

Diethylene glycol

The inclusion of sweet-tasting but toxic diethylene glycol in Chinese-made toothpaste led to a several nation, multiple brand toothpaste recall in 2007.[14] The world outcry made Chinese officials ban the practice of using diethylene glycol in toothpaste.[15]

Miscellaneous issues and debates

With the exception of toothpaste intended to be used on pets such as dogs and cats, and toothpaste used by astronauts, most toothpaste is not intended to be swallowed, and doing so may cause nausea or diarrheaSony VAIO PCG-7141L battery. 'Tartar fighting' toothpastes have been debated.[16] Case reports of plasma cell gingivitis have been reported with the use of herbal toothpaste containing cinnamon.[17] SLS has been proposed to increase the frequency of mouth ulcers in some people, as it can dry out the protective layer of oral tissues, causing the underlying tissues to become damaged. Sony VAIO PCG-71111L battery

Alteration of taste perception

After using toothpaste, orange juice and other juices have an unpleasant taste. This effect is attributed to products of the chemical reaction between stannous fluoride in toothpaste and the acetic acid in the juices.[19] Sodium lauryl sulfate alters taste perception. It can break down phospholipids that inhibit taste receptors for sweetness, giving food a bitter tasteSony VAIO PCG-61411L battery. In contrast, apples are known to taste more pleasant after using toothpaste.[20] Distinguishing between the hypotheses that the bitter taste of orange juice results from stannous fluoride or from sodium lauryl sulfate is still an unresolved issue and it is thought that the menthol added for flavor may also take part in the alteration of taste perception when binding to lingual cold receptorsSony VAIO PCG-61112L battery.

Other types of toothpaste

Whitening toothpastes

Many toothpastes make whitening claims. Some of these toothpastes contain peroxide, the same ingredient found in tooth bleaching gels. The abrasive in these toothpaste remove the stains, not the peroxide.[21] Whitening toothpaste cannot alter the natural color of teeth or reverse discoloration by penetrating surface stains or decay. To remove surface stainsSony VAIO PCG-61111L battery, whitening toothpaste may include abrasives to gently polish the teeth, and/or additives such as sodium tripolyphosphate to break down or dissolve stains. When used twice a day, whitening toothpaste typically takes two to four weeks to make teeth appear more white. Whitening toothpaste is generally safe for daily use, but excessive use might damage tooth enamel. Teeth whitening gels represent an alternative. Sony VAIO PCG-5T4L battery

Herbal and "natural" toothpastes

Herbal toothpaste from Croatia

Herbal toothpastes are made from natural ingredients and some are even certified as organic. Many consumers have started to switch over to natural toothpastes to avoid synthetic and artificial flavors that are commonly found in regular toothpastes.[22] Due to the increased demand of natural products, most of the toothpaste manufacturers now produce herbal toothpastes. This type of toothpaste does not contain dyes or artificial flavorsSony VAIO PCG-5T3L battery.

Many herbal toothpastes do not contain fluoride or sodium lauryl sulfate. The ingredients found in natural toothpastes vary widely but often include baking soda, aloe, eucalyptus oil, myrrh, plant extract (strawberry extract), and essential oils. In addition to the commercially available products, it is possible to make one's own toothpaste using similar ingredientsSony VAIO PCG-5T2L battery.

History

Early toothpastes

The Greeks, and then the Romans, improved the recipes for toothpaste by adding abrasives such as crushed bones and oyster shells.[23] In the 9th century, the Persian musician and fashion designer Ziryab invented a type of toothpaste, which he popularized throughout Islamic Spain.[24] The exact ingredients of this toothpaste are unknown,[25] but it was reported to have been both "functional and pleasant to taste".Sony VAIO PCG-5S3L battery It is not known whether these early toothpastes were used alone, were to be rubbed onto the teeth with rags, or were to be used with early toothbrushes, such as neem-tree twigs and miswak. Toothpastes or powders came into general use in the 19th century.

Early French toothpowder, 1894.

Tooth powder

Tooth powders for use with toothbrushes came into general use in the 19th century in Britain. Most were homemade, with chalk, pulverized brick, or salt as ingredientsSony VAIO PCG-5S2L battery. A 1866 Home Encyclopedia recommended pulverized charcoal, and cautioned that many patented tooth powders that were commercially marketed did more harm than good.

Arm & Hammer marketed a baking soda-based toothpowder in the United States until approximately 2000, and Colgate currently markets toothpowder in India and other countries.

Modern toothpasteSony VAIO PCG-5S1L battery

Modern toothpaste gel

An 18th century American and British toothpaste recipe called for burnt bread. Another formula around this time called for dragon's blood (a resin), cinnamon, and burnt alum.[26]

Sensodyne Now's toothpaste

By 1900, a paste made of hydrogen peroxide and baking soda was recommended for use with toothbrushes. Pre-mixed toothpastes were first marketed in the 19th century, but did not surpass the popularity of tooth-powder until World War ISony VAIO PCG-5R2L battery. In 1892, Doctor Washington Sheffield of London manufactured toothpaste into a collapsible tube, Dr. Sheffield's Creme Dentifrice. He had the idea after his son traveled to Paris and saw painters using paint from tubes. In York in 1896, Colgate & Company Dental Cream was packaged in collapsible tubes imitating Sheffield. The original collapsible toothpaste tubes were made of lead. Sony VAIO PCG-5R1L battery

Fluoride was first added to toothpastes in the 1890's. "Tanagra", containing calcium fluoride as the active ingredient, was sold by Karl F. Toellner Company, of Bremen, Germany, based upon the early work of chemist Albert Deninger.[29] An analogous invention by Roy Cross, of Kansas City, Mo., was initially criticized by the American Dental Association (ADA) in 1937Sony VAIO PCG-5P4L battery. Fluoride toothpastes developed in the 1950s received the ADA's approval. To develop the first ADA-approved fluoride toothpaste, Procter & Gamble started a research program in the early 1940s. In 1950, Procter & Gamble developed a joint research project team headed by Dr. Joseph Muhler at Indiana University to study new toothpaste with fluoride. In 1955, Procter & Gamble's Crest launched its first clinically proven fluoride-containing toothpasteSony VAIO PCG-5P2L battery. On August 1, 1960, the ADA reported that "Crest has been shown to be an effective anticavity (decay preventative) dentifrice that can be of significant value when used in a conscientiously applied program of oral hygiene and regular professional care." The amount of fluoride in toothpastes varies from country to country.

In 2006 BioRepair appeared in Europe with the first toothpaste containing synthetic hydroxylapatite as an alternative to fluoride for the remineralization and reparation of tooth enamelSony VAIO PCG-5N4L battery. The "biomimetic hydroxylapatite" is intended to protect the teeth by creating a new layer of synthetic enamel around the tooth instead of hardening the existing layer with fluoride that chemically changes it into fluorapatite.[30]

In June 2007, the US Food and Drug Administration and similar agencies in Panama, Puerto Rico and Australia advised consumers to avoid certain brands of toothpaste manufactured in China after some were found to contain the poisonous diethylene glycol, also called diglycol or labeled as "DEG" on the tube. Sony VAIO PCG-5N2L battery

Striped toothpaste

The red area represents the material used for stripes, and the rest is the main toothpaste material. The two materials are not in separate compartments; they are sufficiently viscous that they will not mix. Applying pressure to the tube causes the main material to issue out through the pipe. Simultaneously, some of the pressure is forwarded to the stripe-material, which is then pressed onto the main material through holes in the pipeSony VAIO PCG-51513L battery.

Striped toothpaste was invented by a New Yorker named Leonard Lawrence Marraffino in 1955. The patent (US patent 2,789,731, issued 1957) was subsequently sold to Unilever, who marketed the novelty under the 'Stripe' brand-name in the early 1960s. This was followed by the introduction of the 'Signal' brand in Europe in 1965 (UK patent 813,514). Although 'Stripe' was initially very successfulSony VAIO PCG-51511L battery, it never again achieved the 8% market share that it cornered during its second year.

Marraffino's design, which remains in use for single-color stripes, is simple. The main material, usually white, sits at the crimp end of the toothpaste tube and makes up most of its bulk. A thin pipe, through which that carrier material will flow, descends from the nozzle to it. The stripe-material (this was red in 'Stripe') fills the gap between the carrier material and the top of the tubeSony VAIO PCG-51412L battery. The two materials are not in separate compartments. The two materials are sufficiently viscous that they will not mix. When pressure is applied to the toothpaste tube, the main material squeezes down the thin pipe to the nozzle. Simultaneously, the pressure applied to the main material causes pressure to be forwarded to the stripe material, which then issues out through small holes (in the side of the pipe) onto the main carrier material as it is passing those holesSony VAIO PCG-51411L battery.

In 1990 Colgate-Palmolive was granted a patent (USPTO 4,969,767) for two differently colored stripes. In this scheme, the inner pipe has a cone-shaped plastic guard around it, and about half way up its length. Between the guard and the nozzle-end of the tube is then a space for the material for one color, which then issues out of holes in the pipe. On the other side of the guard is space for second stripe-material, which has its own set of holesSony VAIO PCG-51312L battery.

Striped toothpaste should not be confused with layered toothpaste. Layered toothpaste requires a multi-chamber design (e.g. USPTO 5,020,694), in which two or three layers then extrude out of the nozzle. This scheme, like that of pump dispensers (USPTO 4,461,403), is more complicated (and thus, more expensive to manufacture) than either the Marraffino design or the Colgate designSony VAIO PCG-51311L battery.

The toothbrush is an oral hygiene instrument used to clean the teeth and gums that consists of a head of tightly clustered bristles mounted on a handle, which facilitates the cleansing of hard-to-reach areas of the mouth. Toothpaste, which often contains fluoride, is commonly used in conjunction with a toothbrush to increase the effectiveness of toothbrushingSony VAIO PCG-51211L battery. Toothbrushes are available with different bristle textures, sizes and forms. Most dentists recommend using a toothbrush labelled "soft", since hard bristled toothbrushes can damage tooth enamel and irritate the gums.[1] Toothbrushes have usually been made from synthetic fibers since they were developed, although animal bristles are still sometimes usedSony VAIO PCG-41112L battery.

History

Horsehair toothbrush said to have been used by Napoleon Bonaparte (1769-1821)

A variety of oral hygiene measures have been used since before recorded history.[2] This has been verified by various excavations done all over the world, in which chew sticks, tree twigs, bird feathers, animal bones and porcupine quills were recoveredSony VAIO PCG-3A4L battery.

The earliest description of a toothbrush was made in a Chinese historical work, dated to approximately 1600 BC.[2] It described a chewing stick,[2] consisting of a twig and a frayed end. Various forms of toothbrush have been used. Indian medicine (Ayurveda) used the twigs of the neem or banyan tree to make toothbrushes and other oral-hygiene-related products for millenniaSony VAIO PCG-3A3L battery. The end of a neem twig is chewed until it is soft and splayed, and it is then used to brush the teeth. In the Muslim world, the usage of miswak—a type of chewing stick consisting of the roots or twigs of the Arak tree (Salvadora persica), which have antiseptic properties—is common practice and dates to pre-Islamic times.[3]. Muhammad popularized the use of miswak and some erroneously believe it's his invention[6][7]. Rubbing baking soda or chalk against the teeth has also been common practice in historySony VAIO PCG-3A2L battery.

The first bristle toothbrush was invented in China during the Tang Dynasty (619–907) and used hog bristle.[3][8] In 1223, Japanese Zen master Dōgen Kigen recorded on Shōbōgenzō that he saw monks in China clean their teeth with brushes made of horse-tail hairs attached to an ox-bone handle. The bristle toothbrush spread to Europe, brought back from China to Europe by travellers.[9] It was adopted in Europe during the 17th century. Sony VAIO PCG-3A1L battery Many mass-produced toothbrushes, made with horse or boar bristle, were imported to England from China until the mid-20th century.[2]

A photo from 1899 showing the use of a toothbrush.

The earliest identified use of the word toothbrush in English was in the autobiography of Anthony Wood, who wrote in 1690 that he had bought a toothbrush from J. Barret.[11]

In Europe, William Addis of England is believed to have produced the first mass-produced toothbrush in 1780.[9][12] In 1770 he had been jailed for causing a riotSony VAIO PCG-394L battery; while in prison he decided that the method used to clean teeth – at the time rubbing a rag with soot and salt on the teeth – could be improved, so he took a small animal bone, drilled small holes in it, obtained some bristles from a guard, tied them in tufts, passed the tufts through the holes on the bone, and glued them. He soon became very rich. He died in 1808, and left the business to his eldest son, also called William; the company continues to this day under the name of Wisdom ToothbrushesSony VAIO PCG-393L battery.[13] By 1840 toothbrushes were being mass-produced in England, France, Germany, and Japan.[13] Pig bristle was used for cheaper toothbrushes, and badger hair for the more expensive ones.[13]

The first patent for a toothbrush was by H. N. Wadsworth in 1857 (US Patent No. 18,653) in the United States, but mass production in the USA only started in 1885. The rather advanced design had a bone handle with holes bored into it for the Siberian boar hair bristlesSony VAIO PCG-391L battery. Animal bristle was not an ideal material as it retains bacteria and does not dry well, and the bristles often fell out. In the USA brushing teeth did not become routine until after World War II, when American soldiers had to clean their teeth daily.[12]

A child being shown how to use a toothbrush.

During the 1900s, celluloid handles gradually replaced bone handles in toothbrushes.[3] Natural animal bristles were also replaced by synthetic fibers, usually nylon, by DuPont in 1938. The first nylon bristle toothbrush, made with nylon yarn, went on sale on February 24, 1938Sony VAIO PCG-384L battery. The first electric toothbrush, the Broxodent, was invented in Switzerland in 1954.[14] Today, nylon is widely used for the bristles and the handles are commonly made from thermoplastic materials.[2]

In January 2003 the toothbrush was selected as the number one invention Americans could not live without according to the Lemelson-MIT Invention Index.[15]

Chewable toothbrush

chewable toothbrushes

A chewable toothbrush is a miniature plastic moulded toothbrush that can be used when no water is available. They tend to be very small, but should not be swallowedSony VAIO PCG-383L battery. They are most commonly available from bathroom vending machines. They are available in different flavors such as mint or bubblegum and should be disposed of after use. Other types of disposable toothbrushes, such as those that include a small breakable plastic ball of toothpaste on the bristles, can be used without water and prove to be quite handy to travelersSony VAIO PCG-382L battery.

In chemistry, soap is a salt of a fatty acid.[1] Soaps are mainly used as surfactants for washing, bathing, and cleaning, but they are also used in textile spinning and are important components of lubricants. Soaps for cleansing are obtained by treating vegetable or animal oils and fats with a strongly alkaline solution. Fats and oils are composed of triglycerides: three molecules of fatty acids attached to a single molecule of glycerol. Sony VAIO PCG-381L battery The alkaline solution, often called lye, brings about a chemical reaction known as saponification. In saponification, the fats are first hydrolyzed into free fatty acids, which then combine with the alkali to form crude soap. Glycerol, often called glycerine, is liberated and is either left in or washed out and recovered as a useful by-product according to the process employed. Sony VAIO PCG-7185L battery

Soaps are key components of most lubricating greases, which are usually emulsions of calcium soap or lithium soaps and mineral oil. These calcium- and lithium-based greases are widely used. Many other metallic soaps are also useful, including those of aluminium, sodium, and mixtures of them. Such soaps are also used as thickeners to increase the viscosity of oils. In ancient times, lubricating greases were made by the addition of lime to olive oil. Sony VAIO PCG-7184L battery

Mechanism of cleansing soaps

Structure of a micelle, a cell-like structure formed by the aggregation of soap subunits (such as sodium stearate). The exterior of the micelle is hydrophilic (attracted to water) and the interior is lipophilic (attracted to oils).

When used for cleaning, soap serves as a surfactant in conjunction with water. The cleaning action of this mixture is attributed to the action of micelles, tiny spheres coated on the outside with polar hydrophilic (water-loving) groupsSony VAIO PCG-7183L battery, encasing a lipophilic (fat-loving) pocket that can surround the grease particles, causing them to disperse in water. The lipophilic portion is made up of the long hydrocarbon chain from the fatty acid. In other words, whereas normally oil and water do not mix, the addition of soap allows oils to disperse in water and be rinsed away. Synthetic detergents operate by similar mechanisms to soapSony VAIO PCG-7182L battery.

Effect of the alkali

The type of alkali metal used determines the kind of soap produced. Sodium soaps, prepared from sodium hydroxide, are firm, whereas potassium soaps, derived from potassium hydroxide, are softer or often liquid. Historically, potassium hydroxide was extracted from the ashes of bracken or other plants. Lithium soaps also tend to be hard—these are used exclusively in greasesSony VAIO PCG-7181L battery.

Effects of fats

See also: Total fatty matter

Soaps are derivatives of fatty acids. Traditionally they have been made from triglycerides (oils and fats).[4] Triglyceride is the chemical name for the triesters of fatty acids and glycerin. Tallow, i.e., rendered beef fat, is the most available triglyceride from animals. Its saponified product is called sodium tallowate. Typical vegetable oils used in soap making are palm oilSony VAIO PCG-7174L battery, coconut oil, olive oil, and laurel oil. Each species offers quite different fatty acid content and, hence, results in soaps of distinct feel. The seed oils give softer but milder soaps. Soap made from pure olive oil is sometimes called Castile soap or Marseille soap and is reputed for being extra-mild. The term "Castile" is also sometimes applied to soaps from a mixture of oils, but a high percentage of olive oilSony VAIO PCG-7173L battery.

History of cleansing soaps

Early history

Box for Amigo de Obrero (Worker's friend) soap from 20th century. Part of the Museo del Objeto del Objeto collection

The earliest recorded evidence of the production of soap-like materials dates back to around 2800 BC in Ancient Babylon.[5] In the reign of Nabonidus (556–539 BCE) a recipe for soap consisted of uhulu [ashes], cypress [oil] and sesame [seed oil] "for washing the stones for the servant girls".[6] A formula for soap consisting of water, alkali, and cassia oil was written on a Babylonian clay tablet around 2200 BCSony VAIO PCG-7172L battery.

The Ebers papyrus (Egypt, 1550 BC) indicates that ancient Egyptians bathed regularly and combined animal and vegetable oils with alkaline salts to create a soap-like substance. Egyptian documents mention that a soap-like substance was used in the preparation of wool for weaving.

Roman historySony VAIO PCG-7171L battery

The word sapo, Latin for soap, first appears in Pliny the Elder's Historia Naturalis, which discusses the manufacture of soap from tallow and ashes, but the only use he mentions for it is as a pomade for hair; he mentions rather disapprovingly that the men of the Gauls and Germans were more likely to use it than their female counterparts.[7] Aretaeus of Cappadocia, writing in the first century AD, observes among "Celts, which are men called GaulsSony VAIO PCG-7162L battery, those alkaline substances that are made into balls, called soap".[8]

A popular belief encountered in some places claims that soap takes its name from a supposed Mount Sapo, where animal sacrifices were supposed to take place—tallow from these sacrifices would then have mixed with ashes from fires associated with these sacrifices and with water to produce soap. But there is no evidence of a Mount Sapo within the Roman world and no evidence for the apocryphal storySony VAIO PCG-7161L battery. The Latin word sapo simply means "soap"; it was likely borrowed from an early Germanic language and is cognate with Latin sebum, "tallow", which appears in Pliny the Elder's account.[9] Roman animal sacrifices usually burned only the bones and inedible entrails of the sacrificed animals; edible meat and fat from the sacrifices were taken by the humans rather than the godsSony VAIO PCG-7154L battery.

Zosimos of Panopolis, ca. 300 AD, describes soap and soapmaking.[10] Galen describes soap-making using lye and prescribes washing to carry away impurities from the body and clothes. According to Galen, the best soaps were German, and soaps from Gaul were second best. This is a reference to true soap in antiquity. Sony VAIO PCG-7153L battery

Islamic history

Solid soap was virtually unknown in northern Europe until the thirteenth century[citation needed] when it started being imported from Islamic Spain and North Africa. By that time the manufacture of soap in the Islamic world had become virtually industrialized, with sources in Fes, Damascus, and Aleppo. A 12th century Islamic document has the world's first extant description of the process of soap production. Sony VAIO PCG-7152L battery Mentioning the key ingredient, alkali, which later becomes crucial to modern chemistry, derived from al-qaly or "ashes".

Medieval history

Soap-makers in Naples were members of a guild in the late sixth century,[12] and in the 8th century, soap-making was well known in Italy and Spain.[13] The Carolingian capitulary De Villis, dating to around 800, representing the royal will of Charlemagne, mentions soap as being one of the products the stewards of royal estates are to tallySony VAIO PCG-7151L battery. Soap-making is mentioned both as "women's work" and as the produce of "good workmen" alongside other necessities such as the produce of carpenters, blacksmiths, and bakers.[14]

15th–20th centuries

Ad for Pear' Soap, 1889

1922 magazine advertisement for Palmolive Soap.

Liquid soap

Manufacturing process of soaps/detergents

In France, by the second half of the 15th century, the semi-industrialized professional manufacture of soap was concentrated in a few centers of Provence— Toulon, Hyères, and Marseille — which supplied the rest of France. 
Sony VAIO PCG-7148L battery In Marseilles, by 1525, production was concentrated in at least two factories, and soap production at Marseille tended to eclipse the other Provençal centers.[16] English manufacture tended to concentrate in London.[17]

Finer soaps were later produced in Europe from the 16th century, using vegetable oils (such as olive oil) as opposed to animal fats. Many of these soaps are still produced, both industrially and by small-scale artisansSony VPCW21M2E/WI battery. Castile soap is a popular example of the vegetable-only soaps derived by the oldest "white soap" of Italy.

In modern times, the use of soap has become universal in industrialized nations due to a better understanding of the role of hygiene in reducing the population size of pathogenic microorganisms. Industrially manufactured bar soaps first became available in the late eighteenth century, as advertising campaigns in Europe and the United States promoted popular awareness of the relationship between cleanliness and health. Sony VPCW21C7E battery

Until the Industrial Revolution, soapmaking was conducted on a small scale and the product was rough. Andrew Pears started making a high-quality, transparent soap in 1789 in London. His son-in-law, Thomas J. Barratt, opened a factory in Isleworth in 1862. William Gossage produced low-price good-quality soap from the 1850s. Robert Spear Hudson began manufacturing a soap powder in 1837, initially by grinding the soap with a mortar and pestleSony VPCW12S1E/WZ battery. American manufacturer Benjamin T. Babbitt introduced marketing innovations that included sale of bar soap and distribution of product samples. William Hesketh Lever and his brother, James, bought a small soap works in Warrington in 1886 and founded what is still one of the largest soap businesses, formerly called Lever Brothers and now called Unilever. These soap businesses were among the first to employ large-scale advertising campaignsSony VPCW12S1E/W battery.

Soap making processes

The industrial production of soap involves continuous processes, involving continuous addition of fat and removal of product. Smaller-scale production involve the traditional batch processes. There are three variations: the cold-process, wherein the reaction takes place substantially at room temperature, the semi-boiled or hot-process, wherein the reaction takes place at near-boiling point, and the fully boiled processSony VPCW12S1E/T battery, wherein the reactants are boiled at least once and the glycerol recovered. The cold-process and hot-process (semi-boiled) are the simplest and typically used by small artisans and hobbyists producing handmade decorative soaps and similar. The glycerine remains in the soap and the reaction continues for many days after the soap is poured into moulds. The glycerine is left during the hot-process methodSony VPCW12S1E/P battery, but at the high temperature employed the reaction is practically completed in the kettle, before the soap is poured into moulds. This process is simple and quick and is the one employed in small factories all over the world.

Handmade soap from the cold process also differs from industrially made soap in that an excess of fat is used, beyond that which is used to consume the alkali (in a cold-pour process this excess fat called "superfatting"), and the glycerine left in acts as a moisturizing agentSony VPCW11S1E/W battery. However, the glycerine also makes the soap softer and less resistant to becoming "mushy" if left wet. Since it is better to add too much oil and have left-over fat, than to add too much lye and have left-over lye, soap produced from the hot process also contains left-over glycerine and its concommitant pros and cons. Further addition of glycerine and processing of this soap produces glycerin soapSony VPCW11S1E/T battery. Superfatted soap is more skin-friendly than one without extra fat. However, if too much fat is added, it can leave a "greasy" feel to their skin. Sometimes an emollient additive such as jojoba oil or shea butter is added "at trace" (i.e., the point at which the saponification process is sufficiently advanced that the soap has begun to thicken in the cold process method) Sony VPCW11S1E/P battery in the belief that nearly all the lye will be spent and it will escape saponification and remain intact. In the case of hot-process soap, an emollient may be added after the initial oils have saponified so that they remain unreacted in the finished soap. Superfatting can also be accomplished through a process known as "lye discount" in which the soap maker uses less alkali than required instead of adding extra fatsSony VPCYA1S1E/B battery.

Cold process

Even in the cold-soapmaking process, some heat is usually required; the temperature is usually raised to a point sufficient to ensure complete melting of the fat being used. The batch may also be kept warm for some time after mixing to ensure that the alkali (hydroxide) is completely used up. This soap is safe to use after approximately 12–48 hours but is not at its peak quality for use for several weeksSony VPCYA1V9E/B battery.

Cold-process soapmaking requires exact measurements of lye and fat amounts and computing their ratio, using saponification charts to ensure that the finished product does not contain any excess hydroxide or too much free unreacted fat. Saponification charts should also be used in hot-processes, but are not necessary for the "fully boiled hot-process" soapingSony VPCY22Z5008B battery.

A cold-process soapmaker first looks up the saponification value of the fats being used on a saponification chart. This value is used to calculate the appropriate amount of lye. Excess unreacted lye in the soap will result in a very high pH and can burn or irritate skin; not enough lye and the soap is greasy. Most soap makers formulate their recipes with a 4–10% deficit of lye so that all of the lye is converted and that excess fat is left for skin conditioning benefitsSony VPCY21S1E/SI battery.

The lye is dissolved in water. Then oils are heated, or melted if they are solid at room temperature. Once the oils are liquified and the lye is fully dissolved in water, they are combined. This lye-fat mixture is mixed until the two phases (oils and water) are fully emulsified. Emulsification is most easily identified visually when the soap exhibits some level of "trace"Sony VPCY21S1E/L battery, which is the thickening of the mixture. (Modern-day amateur soapmakers often use a stick blender to speed this process). There are varying levels of trace. Depending on how additives will affect trace, they may be added at light trace, medium trace, or heavy trace. After much stirring, the mixture turns to the consistency of a thin pudding. "Trace" corresponds roughly to viscositySony VPCY21S1E/G battery. Essential oils and fragrance oils can be added with the initial soaping oils, but solid additives such as botanicals, herbs, oatmeal, or other additives are most commonly added at light trace, just as the mixture starts to thicken.

Handmade soaps sold at a shop in Hyères, France

Traditional Marseille soap

The batch is then poured into moulds, kept warm with towels or blankets, and left to continue saponification for 12 to 48 hours. (Milk soaps or other soaps with sugars added are the exceptionSony VPCY11S1E/S battery. They typically do not require insulation, as the presence of sugar increases the speed of the reaction and thus the production of heat.) During this time, it is normal for the soap to go through a "gel phase," wherein the opaque soap will turn somewhat transparent for several hours, before once again turning opaque.

After the insulation period, the soap is firm enough to be removed from the mould and cut into bars. At this time, it is safe to use the soapSony VPCY11S1E battery, since saponification is in essence complete. However, cold-process soaps are typically cured and hardened on a drying rack for 2–6 weeks before use. During this cure period, trace amounts of residual lye is consumed by saponification and excess water evaporates.

During the curing process, some molecules in the outer layer of the solid soap react with the carbon dioxide of the air and produce a dusty sheet of sodium carbonate. This reaction is more intense if the mass is exposed to wind or low temperaturesSony VPCZ11X9E/B battery.

Hot processes

Hot-processed soaps are created by encouraging the saponification reaction by adding heat to the reaction. This speeds the reaction. Unlike cold-processed soap, in hot-process soaping the oils are completely saponified by the end of the handling period, whereas with cold pour soap the bulk of the saponification happens after the oils and lye solution emulsification is poured into mouldsSony VPCZ11Z9E/B battery.

In the hot-process, the hydroxide and the fat are heated and mixed together 80–100 °C, a little below boiling point, until saponification is complete, which, before modern scientific equipment, the soapmaker determined by taste (the sharp, distinctive taste of the hydroxide disappears after it is saponified) or by eye; the experienced eye can tell when gel stage and full saponification has occurred. Beginners can find this information through research and classesSony VPCZ12M9E/B battery. Tasting soap for readiness is not recommended, as sodium and potassium hydroxides, when not saponified, are highly caustic.

An advantage of the fully boiled hot process in soap making is that the exact amount of hydroxide required need not be known with great accuracy. They originated when the purity of the alkali hydroxides were unreliable, as these processes can use even naturally found alkalis such as wood ashes and potash deposits. In the fully boiled processSony VPCZ12X9E/X battery, the mix is actually boiled (100C+), and, after saponification has occurred, the "neat soap" is precipitated from the solution by adding common salt, and the excess liquid drained off. This excess liquid carries away with it much of the impurities and color compounds in the fat, to leave a purer, whiter soap, and with practically all the glycerine removed. The hot, soft soap is then pumped into a mould. The spent hydroxide solution is processed for recovery of glycerineSony VPCZ12Z9E/X battery.

Molds

Many commercially available soap moulds are made of silicone or various types of plastic, although many soap making hobbyists may use cardboard boxes lined with a plastic film. Soaps can be made in long bars that are cut into individual portions, or cast into individual mouldsSony VPCZ138GA battery.

Purification and finishing

A generic bar of soap, after purification and finishing.

In the fully boiled process on factory scale, the soap is further purified to remove any excess sodium hydroxide, glycerol, and other impurities, colour compounds, etc. These components are removed by boiling the crude soap curds in water and then precipitating the soap with salt.

At this stage, the soap still contains too much water, which has to be removed. This was traditionally done on chill rolls, which produced the soap flakes commonly used in the 1940s and 1950sSony VPCZ13M9E/B battery. This process was superseded by spray dryers and then by vacuum dryers.

The dry soap (approximately 6–12% moisture) is then compacted into small pellets or noodles. These pellets/noodles are now ready for soap finishing, the process of converting raw soap pellets into a saleable product, usually bars.

Soap pellets are combined with fragrances and other materials and blended to homogeneity in an amalgamator (mixer) Sony VPCZ13M9E/X battery. The mass is then discharged from the mixer into a refiner, which, by means of an auger, forces the soap through a fine wire screen. From the refiner, the soap passes over a roller mill (French milling or hard milling) in a manner similar to calendering paper or plastic or to making chocolate liquor. The soap is then passed through one or more additional refiners to further plasticize the soap massSony VPCZ13V9E battery. Immediately before extrusion, the mass is passed through a vacuum chamber to remove any trapped air. It is then extruded into a long log or blank, cut to convenient lengths, passed through a metal detector, and then stamped into shape in refrigerated tools. The pressed bars are packaged in many ways.

(Azul e branco soap) – A bar of blue-white soap

Sand or pumice may be added to produce a scouring soap. The scouring agents serve to remove dead skin cells from the surface being cleanedSony VPCZ13X5003B battery. This process is called exfoliation. Many newer materials that are effective but do not have the sharp edges and poor particle size distribution of pumice are used for exfoliating soaps.

Nanoscopic metals are commonly added to certain soaps specifically for both colouration and anti-bacterial properties. Titanium powder is commonly used in extreme "white" soaps for these purposes; nickel, aluminium, and silver are less commonly usedSony VPCZ13V9E/X battery. These metals exhibit an electron-robbing behaviour when in contact with bacteria, stripping electrons from the organism's surface, thereby disrupting their functioning and killing them. Because some of the metal is left behind on the skin and in the pores, the benefit can also extend beyond the actual time of washing, helping reduce bacterial contamination and reducing potential odours from bacteria on the skin surfaceSony VPCZ13Z9E/X battery.