The
domestic cat[1][2] (
Felis catus[2] or
Felis silvestris catus[4]) is a small, usually
furry,
domesticated, and
carnivorous mammal. It is often called the
housecat when kept as an indoor pet,
[6] or simply the
cat when there is no need to distinguish it from other
felids and
felines. Cats are often valued by humans for companionship and their ability to hunt
vermin and household pests.
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.
Cat senses fit a
crepuscular and predatory
ecological niche. Cats can hear sounds too faint or too high in
frequency
for human ears, such as those made by mice and other small animals.
They can see in near darkness. Like most other mammals, cats have poorer
color vision and a 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 (
meowing,
purring,
trilling, hissing,
growling and
grunting) as well as
cat pheromones and types of
cat-specific body language.
[7]
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, requiring
population control.
[8]
Since cats were
cult animals in ancient Egypt, they were commonly believed to have been domesticated there,
[9] but there may have been instances of domestication as early as the
Neolithic from around 9500 years ago (7500 BCE).
[10]
A genetic study in 2007 revealed that domestic cats are descended from
African wildcats (
Felis silvestris lybica) c. 8000 BCE, in the Middle East.
[9][11] According to
Scientific American, cats are the most popular pet in the world, and are now found almost every place where people live.
[12]
Nomenclature and etymology
Classification based on human interaction[13]
| Population |
Food source |
Shelter |
Socialized |
| Pedigree |
Fed by guardian |
Human guardian |
Yes |
| Pet |
Fed by guardian |
Human homes |
Yes |
| Semi-feral |
General feeding |
Buildings |
Yes |
| Feral |
General feeding/foraging |
Buildings |
No |
The English word
cat (
Old English catt) is in origin a loanword, introduced to many
languages of Europe from Latin
cattus[14] and
Byzantine Greek κάττα, including
Portuguese and
Spanish gato,
French chat,
German Katze,
Lithuanian katė and
Old Church Slavonic kotka, among others.
[15] The ultimate source of the word is
Afroasiatic, presumably from
Late Egyptian čaute,
[16] the feminine of
čaus "wildcat". The word was introduced, together with the domestic animal itself, to the
Roman Republic by the 1st century BCE.
[citation needed] 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, related to
Swedish kattepus, or
Norwegian pus,
pusekatt. Similar forms exist in Lithuanian
puižė and
Irish puisín. The etymology of this word is unknown, but it may have simply arisen from a sound used to attract a cat.
[17][18]
A group of cats is referred to as a "clowder" or a "glaring",
[19] a male cat is called a "tom" or "tomcat"
[20] (or a "gib",
[21] if neutered), a female is called a "molly"
[citation needed] or (especially among breeders) a "queen",
[22] and a pre-pubescent juvenile is referred to as a "
kitten". The male progenitor of a cat, especially a pedigreed cat, is its "sire",
[23] and its female progenitor is its "dam".
[24] In
Early Modern English, the word
kitten was interchangeable with the now-obsolete word
catling.
[25]
A
pedigreed cat is one whose ancestry is recorded by a
cat fancier organization. A
purebred cat
is one whose ancestry contains only individuals of the same breed. Many
pedigreed and especially purebred cats are exhibited as
show cats. Cats of unrecorded, mixed ancestry are referred to as
domestic short-haired or
domestic long-haired cats, by
coat type, or commonly as random-bred, moggies (chiefly
British), or (using terms borrowed from
dog breeding) mongrels or mutt-cats.
While the
African wildcat
is the ancestral subspecies from which domestic cats are descended, and
wildcats and domestic cats can completely interbreed, there are several
intermediate stages between domestic pet and pedigree cats on the one
hand and those entirely wild animals on the other. The semi-feral cat is
a mostly outdoor cat that is not owned by any one individual, but is
generally friendly to people and may be fed by several households.
Feral cats
are associated with human habitation areas and may be fed by people or
forage in rubbish, but are typically wary of human interaction.
[13]
Taxonomy and evolution
Main article:
Cat evolution
The
wildcat,
Felis silvestris, is the 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,
[26] 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 approximately seven species (depending upon classification scheme).
[1][27] Members of the genus are found worldwide and include the
jungle cat (
Felis chaus) of southeast Asia,
European wildcat (
F. silvestris silvestris),
African wildcat (
F. s. lybica), the
Chinese mountain cat (
F. bieti), and the Arabian
sand cat (
F. margarita), among others.
[28]
All the cats in this genus share a common ancestor that probably lived around 6–7 million years ago in Asia.
[29] The exact relationships within the Felidae are close but still uncertain,
[30][31] e.g. the Chinese mountain cat is sometimes classified (under the name
Felis silvestris bieti) as a
subspecies of the wildcat, like the North African variety
F. s. lybica.
[4][30] As domestic cats are little altered from wildcats, they can readily interbreed. This
hybridization poses a danger to the genetic distinctiveness of wildcat populations, particularly in
Scotland and
Hungary, and possibly also the
Iberian Peninsula.
[32]
The domestic cat was first classified as
Felis catus by
Carolus Linnaeus in the tenth edition of his
Systema Naturae in 1758.
[1][3] However, because of modern
phylogenetics, domestic cats are now usually regarded as another subspecies of the wildcat,
Felis silvestris.
[1][4][33] This has resulted in mixed usage of the terms, as the domestic cat can be called by its subspecies name,
Felis silvestris catus.
[1][4][33] Wildcats have also been referred to as various subspecies of
F. catus,
[33] but in 2003 the
International Commission on Zoological Nomenclature fixed the name for wildcats as
F. silvestris.
[34] 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.
[34] Sometimes the domestic cat has been called
Felis domesticus[35] or
Felis domestica,
[1] as proposed by German naturalist
J. C. P. Erxleben in 1777, but these are not valid taxonomic names and have been used only rarely in scientific literature,
[36] because Linnaeus's binomial takes precedence.
[37]
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, 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.
[38][39] This limited evolution during domestication means that domestic cats tend to interbreed freely with wild relatives,
[32] distinguishing them from other domesticated animals.
[citation needed] Fully domesticated house cats also often interbreed with
feral F. catus populations.
[13] However, several natural behaviors and characteristics of wildcats may have
pre-adapted them for domestication as pets.
[39] These traits include their small size, social nature, obvious body language, love of play, and relatively high intelligence;
[40]:12–17 they may also have an inborn tendency towards tameness.
[39]
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.
[41]
However, this has been criticized as implausible, because there may
have been little reward for such an effort: 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.
[4]
There is a population of Transcaucasus Black feral cats once classified as
Felis daemon (Satunin, 1904), but now population is considered to be a part of domestic cat.
[42]
Genetics
Main article:
Cat genetics
The domesticated cat and its closest wild ancestor are both
diploid organisms that possess 38
chromosomes[43] and roughly 20,000 genes.
[44] About 250 heritable
genetic disorders have been identified in cats, many similar to human
inborn errors.
[45] The high level of similarity among the
metabolisms of mammals allows many 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 as
animal models in the study of the human diseases.
[46][47]
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 4–5 kg (8.8–11 lb).
[30] However, some
breeds, such as the
Maine Coon, can occasionally exceed 11 kg (25 lb). Conversely, very small cats (less than 1.8 kg (4.0 lb)) have been reported.
[48] The world record for the largest cat is 21.3 kg (47 lb).
[49] The smallest adult cat ever officially recorded weighed around 1.36 kg (3.0 lb).
[49] Feral cats tend to be lighter as they have more limited access to food than house cats. In the
Boston area, the average feral adult male will scale 3.9 kg (8.6 lb) and average feral female 3.3 kg (7.3 lb).
[50]
Cats average about 23–25 cm (9–10 in) in height and 46 cm (18.1 in) in
head/body length (males being larger than females), with tails averaging
30 cm (11.8 in) in length.
[51]
Cats have seven
cervical vertebrae as do almost all
mammals; 13
thoracic vertebrae (humans have 12); seven
lumbar vertebrae (humans have five); three
sacral vertebrae like most mammals (humans have five because of their bipedal posture); and a variable number of
caudal vertebrae in the tail (humans retain three to five caudal vertebrae, fused into an internal
coccyx).
[52]: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.
[52] :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 heads.
[53]
The cat skull is unusual among mammals in having very large
eye sockets and a powerful and specialized jaw.
[54]: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.
[55]
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.
[55] 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.
[54]:37
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.
[56] 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. 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 that of most other mammals (and many other
land animals, such as
lizards): the diagonally opposite hind and forelegs will move simultaneously.
[57]
Like almost all members of the
Felidae family, cats have protractable and retractable
claws.
[58] 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
forefeet are typically sharper than those on the hind feet.
[59] 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.
[60] 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". 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 of 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
polydactyly (extra toes and claws).
[60] These are particularly common along the northeast coast of North America.
[61]
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.
[35]
For instance, cats are able to tolerate quite high temperatures: Humans
generally start to feel uncomfortable when their skin temperature
passes about 38 °C (100 °F), but cats show no discomfort until their
skin reaches around 52 °C (126 °F),
[54]:46 and can tolerate temperatures of up to 56 °C (133 °F) if they have access to water.
[63]
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 for heat relief only at very high temperatures
[64]
(but may also pant when stressed). 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.
[65]:1
Cats' feces are comparatively dry and their urine is highly
concentrated, both of which are adaptations that allow cats to retain as
much fluid as possible.
[35] Their kidneys are so efficient that cats can survive on a diet consisting only of meat, with no additional water,
[66] and can even rehydrate by drinking
seawater.
[65]:29[67]
Cats are
obligate carnivores: their
physiology has evolved to efficiently process meat, and they have difficulty digesting plant matter.
[35] 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.
[35] 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.
[68] Another unusual feature is that the cat cannot produce
taurine, with taurine deficiency causing
macular degeneration, wherein the cat's retina slowly degenerates, causing irreversible blindness.
[35]
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.
[35]
A cat's
gastrointestinal tract is 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.
[69] These traits severely limit the cat's ability to digest and use plant-derived nutrients, as well as certain
fatty acids.
[69]
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,
[70] and diets containing no animal products pose the risk of causing severe nutritional deficiencies.
[71]
Cats do eat
grass occasionally. Proposed explanations include that grass is a source of
folic acid or
dietary fiber.
[72]
Senses
Cats' whiskers are highly sensitive to touch.
Cats have excellent
night vision and can see at only one sixth the light level required for human vision.
[54]: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.
[73]
Another adaptation to dim light is the large pupils of cats' eyes.
Unlike some big cats, such as tigers, domestic cats have slit pupils.
[74] 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.
[74] Indeed, at low light levels a cat's pupils will expand to cover most of the exposed surface of its eyes.
[75] 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; they have limited ability to distinguish between red and green.
[76] A 1993 paper found a response to mid-wavelengths from a system other than the
rods
which 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.
[77]
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.
[78][79] Cats do not use this ability to hear
ultrasound for communication but it is probably important in hunting,
[80] since many species of rodents make ultrasonic calls.
[81] Cat hearing is also extremely sensitive and is among the best of any mammal,
[78] being most acute in the range of 500 Hz to 32 kHz.
[82] 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.
[80]
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 square centimetres (0.90 sq in) in
area, which is about twice that of humans and only 1.7-fold less than
the average dog.
[83] Cats are very sensitive to
pheromones such as
3-mercapto-3-methylbutan-1-ol,
[84] which they use to communicate through
urine spraying and marking with
scent glands.
[85] Cats also respond strongly to plants that contain
nepetalactone, especially
catnip, as they can detect that substance at less than one part per billion.
[86] 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.
[87]
Cats have relatively few taste buds compared to humans. Domestic and
wild cats share a gene mutation that keeps their sweet taste buds from
binding to sugary molecules like carbohydrates, leaving them with no
ability to taste
sweetness.
[88] Their
taste buds instead respond to amino acids, bitter tastes and acids.
[89]
To aid with navigation and sensation, cats have dozens of movable
vibrissae
(whiskers) over their body, 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.
[54]:47
