The domesticated cat and its closest wild ancestor are both diploid organisms that possess 38 chromosomes[32] and roughly 20,000 genes.[33] About 250 heritablegenetic disorders have been identified in cats, many similar to human inborn errors.[34] 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 in the study of the human diseases.[35][36]
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.[37] In some breeds of cats congenital deafness is very common, with mostwhite cats (but not albinos) being affected, particularly if they also have blue eyes.[31] 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.[38]
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.[39]Several genes interact to produce cats' hair color and coat patterns. Different combinations of these genes give different phenotypes. For example, the enzymetyrosinase is needed to produce the dark pigment melanin and Burmese cats have a mutant form that is only active at low temperatures, resulting in color appearing only on the cooler ears, tail and paws.[40] A completely inactive gene for tyrosine's is found in albino cats, which therefore lack all pigment.[41] Hair length is determined by the gene for fibroblast growth factor 5, with inactive copies of this gene causing long hair.[42]
Cats have excellent night
vision and
can see at only one-sixth the light level required for human vision.[50]: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.[68] Another
adaptation to dim light is the large pupils of cats' eyes. Unlike some big cats,
such as tigers, domestic cats have slit pupils.[69] 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.[69]Indeed,
at low light levels a cat's pupils will expand to cover most of the exposed
surface of its eyes.[70] 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,[71] although
they can achieve this in some conditions.[72]
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.[73][74] Cats do not use this ability to hear ultrasound for communication but it is probably important in hunting,[75] since many species of rodents make ultrasonic calls.[76] Cat hearing is also extremely sensitive and is among the best of any mammal,[73] being most acute in the range of 500 Hz to 32 kHz.[77] 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.[75]
Free-ranging cats are active both day and night, although they tend to be slightly more
active at night.[104][105] 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 behaviour), as a response to greater human activity at these times.[106]
House cats have territories that vary considerably in size, in one study ranging from
seven to 28 hectares (69 acres).[105] 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.[105] 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. 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
ment sleep accompanied by muscle twitches, which suggests that they are dreaming.[107]
Domestic cats, especially young kittens, are known for their love of play. This behaviour mimics hunting and is important in helping kittens learn to stalk, capture, and kill prey.[136] Cats will also engage in play fighting, with each other and with humans. This behaviour 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.[137]
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.[138] Cats also tend to play with toys more when they are hungry.[139] String is often used as a toy, 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.[140] Owing to the risks posed by cats eating string, it is sometimes replaced with a laser pointer's dot, which cats may chase.[141] While concerns have been raised about the safety of these lasers, Professor John Marshall, an ophthalmologist at St Thomas' Hospital, has stated that it would be "virtually impossible" to blind a cat with a laser pointer.[142]
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