The Anatomy of the Cat

The cat is probably one of the most beautiful and most graceful of all animals. As it 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 bore.

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.

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 up to rounded or pointed tips and stand erect. A cat has keen hearing and can detect many sounds that humans cannot hear. A cat usually turns its head 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. Eyes of the Siamese appear red in the dark; the retinas lack pigment, and the color is provided by blood vessels.