THE ANATOMY OF THE CAT

As the graceful cat moves, the powerful muscles of its long, lithe body ripple under the soft fur, which is often beautifully marked. At rest, every line of its body curves into a graceful arc. The overall impression of the animal sometimes is one of complete indolence. This impression is shattered when the cat springs and attacks with ears flattened and fangs and claws bared.

The cats as a group range widely in size. The great (or "big") cats, including the lion and tiger, are the largest. The domestic cat is one of the smallest. An adult domestic cat is about 8 to 10 inches (20 to 25 centimeters) high. The length from the tip of the nose to the base of the tail averages 18 to 20 inches (46 to 51 centimeters), and the tail is about 10 to 15 inches (25 to 38 centimeters) long. Females usually weigh from 6 to 10 pounds (2.7 to 4.5 kilograms) and males from 10 to 15 pounds (4.5 to 6.8 kilograms), depending on skeletal size.

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The Head and Body

The head is large compared with the rest of the body. The nose and jaws are short, so the face seems flat when compared with the faces of many other kinds of animals. The ears are large and flaring at the base. They taper to rounded or pointed tips and stand erect in almost all breeds. A cat has keen hearing and can detect many sounds that humans cannot hear. A cat usually turns its head, not only its eyes, in the direction of a sound. This aids both hearing and vision. In the cat, as in humans, the inner ear--a bony structure of fluid-filled semicircular canals--contains a complicated mechanism for maintaining body balance. It is this mechanism, not the cat's tail, that enables the animal to land on its feet when it falls.

The cat's large and prominent eyes are placed well forward on the head and, like the eyes of humans, they face forward. The cat comes closer than does any other animal except the owl and the ape to having binocular vision similar to that of humans.

The size and position of the eyes permit as much light as possible to enter them and ensure an extensive field of vision--important factors in hunting and nocturnal prowling. A cat cannot see in total darkness, but it can see better in dim light than can most other kinds of animals.

In bright light a cat's pupils contract to narrow vertical slits. But in the dark these slits enlarge to round openings that admit a maximum amount of light. The eyes seem to shine in the dark. This shininess results when even the smallest amount of light strikes a reflective area of iridescent green or yellow crystalline needles in the inner lining of the eye. The eyes of the Siamese cat appear red in the dark; the retinas lack pigment, and the color is provided by blood vessels. A cat is very alert to any movement, but it probably cannot distinguish color. For these reasons, it will pounce when a victim moves but may not attack prey that remains still.

The tip of a cat's nose, the leather, may be black, reddish, or pink and is usually cool and moist. All cats have an acute sense of smell, scenting prey or their favorite delicacies at surprising distances.

A cat's whiskers, or vibrissae, serve as delicate sense organs of touch. Four rows of stiff whiskers grow on the upper lip on each side of the nose. Small groups of whiskers also are situated on other parts of the body including above each eye, on both cheeks, and on the backs of the forepaws. Cutting off the whiskers not only detracts from the animal's appearance but also impairs its ability to feel its way about.

A cat's teeth serve primarily as weapons, as well as for tearing food. The animal has 30 permanent teeth. The strongest and sharpest are the four large, curved, pointed fangs (canines). With these teeth the cat grasps and tears its food or an enemy. The small front teeth (upper and lower incisors) function chiefly as grooming aids. The cat has fewer side teeth (premolars and molars) than do most other mammals. In most mammals the side teeth are used for grinding food. The cat uses these teeth only for cutting.

A cat's tongue is rough. The tongue of a domestic cat feels much like coarse sandpaper. The tongue of a big wild cat, such as the lion or the tiger, is much rougher. The tongue surface is covered with rasplike projections or barbs that face backward into the throat. All cats use their tongues as a major grooming tool to clean and comb the fur, but they also use them as efficient tools to strip flesh off the bones of prey.

Although a cat's jaws are short, they are extremely strong. They clamp down upon prey with enough power to crush the bones. The lower jaw is attached to the upper one by means of a simple hinge. This arrangement permits only up-and-down motion. A cat cannot move its lower jaw sideways, nor can it grind its teeth. When a cat clamps its jaws shut, the teeth mesh side by side, somewhat like the meshing of gears. So cats tear and crush their food, but they do not chew it. Much of the food is swallowed whole, and digestive juices break it down for use.

All cats--domestic and wild--can and do purr. The sound may be very loud or so soft as to be inaudible to the human ear. Kittens may begin to purr a few days after birth. In all animals, vocal sounds come from vibrations of the vocal cords, which are in the voice box in the throat. No one knows exactly how the cat uses these to produce purring nor why no other kind of animal purrs. In addition to purring, cats make several different kinds of sounds--including meowing, chirping, hissing, yowling, and even growling.

Perhaps among the most striking things about a cat are its litheness and grace of movement and the amazing flexibility of its body. It can with ease roll up into a ball, double up sideways, stretch the back into almost a straight line, or arch it until front and back legs are only a few inches apart. It can turn its body easily so that its tongue can reach the fur on the center of its back for grooming.

The Legs and Feet

The legs appear short when compared with the length of the body, but they are powerful. Strong muscles produce instant power for leaping upon prey or for great bursts of speed to catch prey on the run. The sharp angles of the knee and "heel" of the hind legs also contribute to the power for sudden sprints, for climbing, and for jumping. The front legs are also powerful and extremely flexible. A cat can stretch its forelegs wide apart to hug the body of an enemy and hold it close. The forepaws can be tucked under the chest when the animal crouches, can be curved around the head when the animal washes behind the ears, and can be turned palm up for washing under and between the toes. Most cats have five toes in the forepaws and four in the hind paws. Some domestic cats, especially in the northeastern United States, have extra toes on the inner sides of the front feet or of all feet. This oddity, polydactylism, is an inherited dominant trait. Cats with this trait are prized by many owners.

Male and Female

Cats reproduce so prolifically that there are millions more cats than good homes. Female cats come into heat repeatedly and may become nervous or ill-tempered and lose weight if not permitted to mate. Males wander restlessly, cry loudly to get out, and spray strong-smelling urine about the premises.

To prevent undesired kittens, females may be spayed after 5 or 6 months of age. Males may be neutered after 8 to 10 months to keep them from spraying or wandering. Both operations must be performed by a veterinarian. Neutered cats may need to have their food intake reduced to keep them from gaining weight.

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