Cat
The cat (Felis catus) is a domestic species of small carnivorous mammal.[1][2] It is the only domesticated species in the family Felidae and is often referred to as the domestic cat to distinguish it from the wild members of the family.[4] A cat can either be a house cat, a farm cat or a feral cat; the latter ranges freely and avoids human contact.[5] Domestic cats are valued by humans for companionship and their ability to hunt pests such as rodents. About 60 cat breeds are recognized by various cat registries.[6]
The cat is similar in anatomy to the other felid species: it has a strong flexible body, quick reflexes, sharp teeth and retractable claws adapted to killing small prey. Its night vision and sense of smell are well developed. Cat communication includes vocalizations like meowing, purring, trilling, hissing, growling and grunting as well as cat-specific body language. It is a solitary hunter but a social species. It can hear sounds too faint or too high in frequency for human ears, such as those made by mice and other small mammals. It is a predator that is most active at dawn and dusk.[7] It secretes and perceives pheromones.[8]
Female domestic cats can have kittens from spring to late autumn, with litter sizes ranging from two to five kittens.[9] Domestic cats are bred and shown at events as registered pedigreed cats, a hobby known as cat fancy. Failure to control breeding of pet cats by spaying and neutering, as well as abandonment of pets, resulted in large numbers of feral cats worldwide, contributing to the extinction of entire bird species and evoking population control.[10]
It was long thought that cat domestication was initiated in Ancient Egypt, because cats in ancient Egypt were venerated since around 3100 BC.[11][12] However, the earliest indication for the taming of an African wildcat (F. lybica) was found in Cyprus, where a cat skeleton was excavated close by a human Neolithic grave dating to around 7500 BC.[13] African wildcats were probably first domesticated in the Near East.[14]
As of 2017, the domestic cat was the second-most popular pet in the United States by number of pets owned, after freshwater fish,[15] with 95 million cats owned.[16][17] In the United Kingdom, around 7.3 million cats lived in more than 4.8 million households as of 2019.[18]
Etymology and naming
The origin of the English word 'cat', Old English catt, is thought to be the Late Latin word cattus, which was first used at the beginning of the 6th century.[19] It was suggested that the word 'cattus' is derived from an Egyptian precursor of Coptic ϣⲁⲩ šau, "tomcat", or its feminine form suffixed with -t.[20] The Late Latin word is also thought to be derived from Afro-Asiatic languages.[21] The Nubian word kaddîska "wildcat" and Nobiin kadīs are possible sources or cognates.[22] The Nubian word may be a loan from Arabic قَطّ qaṭṭ ~ قِطّ qiṭṭ. It is "equally likely that the forms might derive from an ancient Germanic word, imported into Latin and thence to Greek and to Syriac and Arabic".[23] The word may be derived from Germanic and Northern European languages, and ultimately be borrowed from Uralic, cf. Northern Sami gáđfi, "female stoat", and Hungarian hölgy, "stoat"; from Proto-Uralic *käďwä, "female (of a furred animal)".[24]
The English puss, extended as pussy and pussycat, is attested from the 16th century and may have been introduced from Dutch poes or from Low German puuskatte, related to Swedish kattepus, or Norwegian pus, pusekatt. Similar forms exist in Lithuanian puižė and Irish puisín or puiscín. The etymology of this word is unknown, but it may have simply arisen from a sound used to attract a cat.[25][26]
A male cat is called a tom or tomcat[27] (or a gib,[28] if neutered) An unspayed female is called a queen,[29] especially in a cat-breeding context. A juvenile cat is referred to as a kitten. In Early Modern English, the word kitten was interchangeable with the now-obsolete word catling.[30] A group of cats can be referred to as a clowder or a glaring.[31]
Taxonomy
The scientific name Felis catus was proposed by Carl Linnaeus in 1758 for a domestic cat.[1][2] Felis catus domesticus was proposed by Johann Christian Polycarp Erxleben in 1777.[3] Felis daemon proposed by Konstantin Alekseevich Satunin in 1904 was a black cat from the Transcaucasus, later identified as a domestic cat.[32][33]
In 2003, the International Commission on Zoological Nomenclature ruled that the domestic cat is a distinct species, namely Felis catus.[34][35] In 2007, it was considered a subspecies of the European wildcat, F. silvestris catus, following results of phylogenetic research.[36][37] In 2017, the IUCN Cat Classification Taskforce followed the recommendation of the ICZN in regarding the domestic cat as a distinct species, Felis catus.[38]
Evolution
The domestic cat is a member of the Felidae, a family that had a common ancestor about 10–15 million years ago.[39] The genus Felis diverged from the Felidae around 6–7 million years ago.[40] Results of phylogenetic research confirm that the wild Felis species evolved through sympatric or parapatric speciation, whereas the domestic cat evolved through artificial selection.[41] The domesticated cat and its closest wild ancestor are both diploid organisms that possess 38 chromosomes[42] and roughly 20,000 genes.[43] The leopard cat (Prionailurus bengalensis) was tamed independently in China around 5500 BC. This line of partially domesticated cats leaves no trace in the domestic cat populations of today.[44]
Domestication
The earliest known indication for a tamed African wildcat was excavated close by a human grave in Shillourokambos, southern Cyprus, dating to about 9,200 to 9,500 years before present. As there is no evidence of native mammalian fauna on Cyprus, the inhabitants of this Neolithic village most likely brought the cat and other wild mammals to the island from the Middle Eastern mainland.[13] Scientists therefore assume that African wildcats were attracted to early human settlements in the Fertile Crescent by rodents, in particular the house mouse (Mus musculus), and were tamed by Neolithic farmers. This commensal relationship between early farmers and tamed cats lasted thousands of years. As agricultural practices spread, so did tame and domesticated cats.[14][6] Wildcats of Egypt contributed to the maternal gene pool of the domestic cat at a later time.[45] The earliest known evidence for the occurrence of the domestic cat in Greece dates to around 1200 BC. Greek, Phoenician, Carthaginian and Etruscan traders introduced domestic cats to southern Europe.[46] During the Roman Empire they were introduced to Corsica and Sardinia before the beginning of the 1st millennium.[47] By the 5th century BC, they were familiar animals around settlements in Magna Graecia and Etruria.[48] By the end of the Roman Empire in the 5th century, the Egyptian domestic cat lineage had arrived in a Baltic Sea port in northern Germany.[45]
During domestication, cats have undergone only minor changes in anatomy and behavior, and they are still capable of surviving in the wild. Several natural behaviors and characteristics of wildcats may have preadapted them for domestication as pets. These traits include their small size, social nature, obvious body language, love of play and relatively high intelligence. Captive Leopardus cats may also display affectionate behavior toward humans, but were not domesticated.[49] House cats often mate with feral cats,[50] producing hybrids such as the Kellas cat in Scotland.[51] Hybridisation between domestic and other Felinae species is also possible.[52]
Development of cat breeds started in the mid 19th century.[53] An analysis of the domestic cat genome revealed that the ancestral wildcat genome was significantly altered in the process of domestication as specific mutations were selected to develop cat breeds.[54] Most breeds are founded on random-bred domestic cats. Genetic diversity of these breeds varies between regions, and is lowest in purebred populations, which show more than 20 deleterious genetic disorders.[55]
Characteristics
Size
The domestic cat has a smaller skull and shorter bones than the European wildcat.[56] It averages about 46 cm (18 in) in head-to-body length and 23–25 cm (9.1–9.8 in) in height, with about 30 cm (12 in) long tails. Males are larger than females.[57] Adult domestic cats typically weigh between 4 and 5 kg (8.8 and 11.0 lb).[41]
Skeleton
Cats have seven cervical vertebrae (as do most mammals); 13 thoracic vertebrae (humans have 12); seven lumbar vertebrae (humans have five); three sacral vertebrae (as do most mammals, but humans have five); and a variable number of caudal vertebrae in the tail (humans have only vestigial caudal vertebrae, fused into an internal coccyx).[58]: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.[58] :16 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 head.[59]
Skull
The cat skull is unusual among mammals in having very large eye sockets and a powerful specialized jaw.[60]:35 Within the jaw, cats have teeth adapted for killing prey and tearing meat. When it overpowers its prey, 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.[61] Compared to other felines, domestic cats have narrowly spaced canine teeth relative to the size of their jaw, which is an adaptation to their preferred prey of small rodents, which have small vertebrae.[61] The premolar and first molar together compose the carnassial pair on each side of the mouth, 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, and cats are largely incapable of mastication.[60]:37 Although cats tend to have better teeth than most humans, with decay generally less likely because of a thicker protective layer of enamel, a less damaging saliva, less retention of food particles between teeth, and a diet mostly devoid of sugar, they are nonetheless subject to occasional tooth loss and infection.[62]
Ambulation
The cat is digitigrade. It walks on the toes, with the bones of the feet making up the lower part of the visible leg.[63] Unlike most mammals, it uses a "pacing" gait and moves both legs on one side of the body before the legs on the other side. It registers directly by placing each hind paw close to the track of the corresponding fore paw, minimizing noise and visible tracks. This also provides sure footing for hind paws when navigating rough terrain. As it speeds up walking to trotting, its gait changes to a "diagonal" gait: the diagonally opposite hind and fore legs move simultaneously.[64]
Claws
Cats have protractable and retractable claws.[65] In their normal, relaxed position, the claws are sheathed with the skin and fur around the paw's 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 fore feet are typically sharper than those on the hind feet.[66] 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. Cats shed the outside layer of their claw sheaths when scratching rough surfaces.[67]
Most cats have five claws on their front paws, and four on their rear paws. The dewclaw is proximal to the other claws. More proximally is a protrusion which appears to be a sixth "finger". This special feature of the front paws, on the inside of the wrists has no function in normal walking, but is thought to be an antiskidding device used while jumping. Some cat breeds are prone to having extra digits (polydactyly).[68] Polydactylous cats occur along North America's northeast coast and in Great Britain.[69]
Senses
Cats have excellent night vision and can see at only one-sixth the light level required for human vision.[60]: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] Large pupils are an adaptation to dim light. The domestic cat has slit pupils, which allow it to focus bright light without chromatic aberration.[71] At low light, a cat's pupils expand to cover most of the exposed surface of its eyes.[72] However, the domestic cat has rather poor color vision and only two types of cone cells, optimized for sensitivity to blue and yellowish green; its ability to distinguish between red and green is limited.[73] A response to middle wavelengths from a system other than the rod cells might be due to a third type of cone. However, this appears to be an adaptation to low light levels rather than representing true trichromatic vision.[74]
Hearing
The domestic cat's hearing is most acute in the range of 500 Hz to 32 kHz.[75] It can detect an extremely broad range of frequencies ranging from 55 Hz to 79,000 Hz. It can hear a range of 10.5 octaves, while humans and dogs can hear ranges of about 9 octaves.[76][77] Its hearing sensitivity is enhanced by its large movable outer ears, the pinnae, which amplify sounds and help detect the location of a noise. It can detect ultrasound, which enables it to detect ultrasonic calls made by rodent prey.[78][79]
Smell
Cats have an acute sense of smell, due in part to their well-developed olfactory bulb and a large surface of olfactory mucosa, about 5.8 cm2 (0.90 in2) in area, which is about twice that of humans.[80] Cats and many other animals have a Jacobson's organ in their mouths that is used in the behavioral process of flehmening. It allows them to sense certain aromas in a way that humans cannot. Cats are sensitive to pheromones such as 3-mercapto-3-methylbutan-1-ol,[81] which they use to communicate through urine spraying and marking with scent glands.[82] Many 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] About 70–80% of cats are affected by nepetalactone.[84] This response is also produced by other plants, such as silver vine (Actinidia polygama) and the herb valerian; it may be caused by the smell of these plants mimicking a pheromone and stimulating cats' social or sexual behaviors.[85]
Taste
Cats have relatively few taste buds compared to humans (470 or so versus more than 9,000 on the human tongue).[86] Domestic and wild cats share a taste receptor gene mutation that keeps their sweet taste buds from binding to sugary molecules, leaving them with no ability to taste sweetness.[87] Their taste buds instead respond to acids, amino acids like protein, and bitter tastes.[88] Cats also have a distinct temperature preference for their food, preferring food with a temperature around 38 °C (100 °F) which is similar to that of a fresh kill and routinely rejecting food presented cold or refrigerated (which would signal to the cat that the "prey" item is long dead and therefore possibly toxic or decomposing)
ليست هناك تعليقات:
إرسال تعليق