CAT

The cat (Felis silvestris catus), also known as the domestic cat or housecat to distinguish it from other felines and felids, is a small carnivorous mammal that is valued by humans for its companionship and its ability to hunt vermin and household pests. Cats have been associated with humans for at least 9,500 years, and are currently the most popular pet in the world. Due to their close association with humans, cats are now found almost everywhere on Earth. This extreme adaptability and Etheir worrying impacts on native animals has led to them being classed as an invasive species. Most of these problems are caused by the large number of feral cats worldwide, with a population of up to 60 million of these animals in the United States alone.



Cats are similar in size and anatomy to the other Felids, with light, flexible bodies and teeth adapted to killing small prey. A skilled predator, the cat hunts over 1,000 species for food, using its excellent eyesight and hearing. Unusually, cats have lost the ability to taste sugar and in some breeds show hereditary deafness. Despite being solitary hunters, cats are a social species and use a variety of vocalizations, pheromones and types of body language for communication. These include meowing, purring, trilling, hissing, growling, squeaking, chirping, clicking, and grunting. They are also bred and shown as registered pedigree pets. This hobby is known as cat fancy.
Until recently the cat was commonly believed to have been domesticated in ancient Egypt, where it was a cult animal. A study in 2007 found that the lines of descent of all house cats probably run through as few as five self-domesticating African Wildcats (Felis silvestris lybica) circa 8000 BC, in the Near East. The earliest direct evidence of cat domestication is a kitten that was buried with its owner 9,500 years ago in Cyprus.

A. ANATOMY

Diagram of the general anatomy of a male cat
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 (46 lb 15.2 oz). The smallest adult cat ever officially recorded weighed around 1.36 kilograms (3 lb). 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.
Cats have 7 cervical vertebrae like almost all mammals, 13 thoracic vertebrae (humans have 12), 7 lumbar vertebrae (humans have 5), 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). 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. Unlike human arms, cat forelimbs are attached to the shoulder by free-floating clavicle bones, which allows them to pass their body through any space into which they can fit their heads.

Skull of a domestic cat.
The cat skull is unusual among mammals in having very large eye sockets and a powerful and specialized jaw. Within the jaw, cats have teeth adapted for killing prey and tearing meat. When they overpower prey, a cat delivers a lethal neck bite with its two long canine teeth that insert between two of the prey's vertebrae and sever its spinal cord, causing irreversible paralysis and death. 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. 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.
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. 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.
Like almost all members of the Felidae family, cats have protractable claws. 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. 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 (bedspreads, thick rugs, etc.). It is also possible to make a cooperative cat extend its claws by carefully pressing both the top and bottom of the paw.

Most cats have five claws on their front paws, and four on their rear paws. 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 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. These are particularly common along the North-East coast of North America.

B. REPRODUCTION

When cats mate, the male tom bites the scruff of the female's neck as she assumes a position conducive to mating.
Female cats are seasonally polyestrous, which means they may have many periods of heat over the course of a year, the season beginning in January or February and ending in late October. Heat periods occur about every two weeks and last about 4 to 7 days. 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. This is because a male cat's penis has a band of about 120-150 backwards-pointing spines, which are about one millimeter long; upon withdrawal of the penis, the spines rake the walls of the female's vagina, which is a trigger for ovulation. After mating, the female will wash her vulva thoroughly. If a male attempts to breed 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.
Because ovulation is not always triggered by a single mating, females may not be impregnated by the first male with which they mate. 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.

A kitten with newly-open eyes.
The gestation period for cats is between 64–67 days, with an average length of 66 days. 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, and cats normally reach sexual maturity at 5–10 months (females) and to 5–7 months (males), although this can vary depending on breed. Females can have two to three litters per year, so may produce up to 150 kittens in their breeding span of around ten years.
Cats are ready to go to new homes at about 12 weeks old, or when they are ready to leave their mother. Cats can be surgically sterilized (spayed or castrated) as early as 7 weeks to limit unwanted reproduction. 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. In the USA approximately 80% of household cats are neutered.
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