Alligator is the name of two kinds of reptiles related to crocodiles. The American alligator lives in the waters and lowlands of southeastern United States. The Chinese alligator lives in the lower Yangtze River Valley, in China. Other closely related reptiles are the caymans of Central and South America. Caymans are often called alligators.

Body. Alligators resemble lizards in their shape, but they have thicker bodies and tails than most lizards. Alligators' jaws are set with many sharp teeth. Their eyes stick up above their skulls so that alligators can see above the water while their bodies are beneath it. They use their short, strong legs for walking. Alligators swim by moving their tails from side to side.
 

An alligator's skin is tough. The skin on the animal's back is rough and ridged with dozens of small bones called osteoderms. The skin on the belly is smooth and was once used to make a handsome, long-lasting leather for handbags, shoes, and other articles. A young American alligator has yellow marks across its body, but these fade after a time. When grown, the American alligator is dull gray and dark olive in color.

Alligators in the past grew to be 18 feet (5.5 meters) long or longer. Today, few can be found that have reached even a length of 12 feet (3.7 meters). Male alligators from 11 to 12 feet (3.4 to 3.7 meters) long weigh from 450 to 550 pounds (204 to 249 kilograms). Females seldom measure more than 9 feet (2.7 meters) long, or weigh over 160 pounds (73 kilograms).

Habits. The female alligator makes her nest of grass and other plants, which she forms into a pile about 3 feet (0.9 meter) high and 7 feet (2.1 meters) across. She lays 20 to 60 eggs in the center of the pile, where the nest is wet. The eggs are white, hard-shelled, and slightly larger than hens' eggs. The young emerge from the eggs after about nine weeks.

Alligators provide more care for their young than do most reptiles. After laying eggs, the female stays near the nest, guarding the eggs against predators. When the young hatch, they give high-pitched yelps, and the mother comes to scratch open the nest and free them. The mother alligator protects her young for a year or more.

When first hatched, the young alligators are about 9 inches (23 centimeters) long. During the first six years of their lives, both males and females grow about 1 foot (30 centimeters) in length each year. After this time, the females grow more slowly. But the males continue to grow at the same rate for several years more. Alligators probably live 50 to 60 years.

In winter, alligators remain resting underwater, bury themselves in mud, or go into deep holes that they have made with their bodies. These holes are called 'gator holes. During droughts, 'gator holes often provide the only refuge for aquatic animals. When rains return, the fish, frogs, turtles, and other animals that have survived in 'gator holes repopulate the swamps and marshy lakes of the South.

Alligators eat many kinds of small animals that live in or near the water, including fish, snakes, frogs, turtles, small mammals, and birds. Large males sometimes attack dogs, pigs, or even cattle. They drag these animals under water to drown them, and then tear them to pieces. Alligators do this by grabbing hold of a part of their prey with their jaws and twisting until that part comes off. Fortunately, even the largest alligators seldom attack human beings. The muscles that close an alligator's jaws are very strong. But once the jaws are shut, they can easily be held closed by a person's bare hands. People have sometimes captured alligators in this way, without using any weapons.

Alligators and crocodiles. Alligators are often mistaken for crocodiles but are different from them in some ways. The fourth tooth of the alligator's lower jaw fits into a pocket of the upper jaw. The same tooth in the crocodile fits into a groove in the side of the upper jaw, making it visible when the animal's mouth is closed. Another way to tell the American alligator from the American crocodile is that the American alligator has a much broader snout. Alligators are also much less aggressive and active than crocodiles. In the United States, alligators and crocodiles are found together only in the marshes at the southern tip of Florida. Both alligators and crocodiles belong to the great group of crocodilians. This group also includes caymans and gavials.

Where alligators live. Alligators were once common in lakes, swamps, and rivers along the Gulf of Mexico and on the Atlantic Coast as far north as North Carolina. They were also found far up the Mississippi River. But so many were killed for their hides or for food and sport that they became scarce. In 1967, the U.S. Fish and Wildlife Service classified the alligator as an endangered species. This designation gave the animal almost complete protection. But by 1977, alligator populations had increased so much in Florida and other southern coastal regions that the animals were reclassified as threatened. This new classification permits tightly regulated hunting of alligators, for commercial purposes.

Scientific classification. Alligators are in the crocodile family, Crocodylidae. They make up the genus Alligator.