The Robinson Library

The Robinson Library >> Order Crocodilia
American Alligator

Alligator mississippiensis


American alligators have been recorded reaching lengths of over 19 feet, but the average size is 8 to 11 feet. They are most readily distinguished from American crocodiles by their teeth. In a crocodile the teeth in the upper and lower jaws are in line, but in the alligator, when its mouth is shut, the upper teeth lie outside the lower. In addition, the alligator's head is broader and shorter and the snout blunter

.American Alligator

Distribution and Habitat

This alligator is restricted to the southeastern United States, below the 35th parallel, and along the Rio Grande River of Texas. It is most commonly found in freshwater swamps, lakes, and bayous, but can tolerate poor water quality areas and brackish marshes along the coast; a few even venture into salt water.


Young alligators feed on insects and freshwater shrips. As they grow older they eat frogs, snakes and fish; mature adults live mainly on fish but will catch muskrats and other small mammals that go down to the water's edge to drink, as well as some waterfowl. Very large alligators are capable of pulling down large mammals such as deer or cows.


Courtship and breeding take place in April and May. Males spend much of the breeding season quarrelling among themselves, while the females essentially "sit back" and wait for the victors. Courtship takes place at night, the pair swimming round faster and faster before finally mating in the water.

The female piles mud and decaying vegetation into a nest mound about 3 feet high, into which she lays 15 to 80 hard-shelled eggs. After laying, the female covers the eggs with another layer of vegetation. She remains by the nest until the eggs hatch 2 to 3 months later, incubated by the heat of the nest's rotting vegetation.

female guarding her nest and eggs

When the eggs are ready to hatch the hatchling alligators peep loudly and the female removes the layer of vegetation over the nest to help them escape. Baby alligators are 8 inches long when first hatched and grow 1 foot a year. Hatchlings remain in groups called pods at least through their first winter and may stay in the vicinity of the nest for 2 to 3 years. The mother may defend her young until the next summer, but this is not a universal trait. Alligators reach sexual maturity at 6 years.

hatchling alligator breaking out of its shell

Other Habits and Behaviors

Females usually have small territories, while males can occupy ranges greater than two square miles.

Conservation Status

American alligators are not endangered, but they are legally protected. They are classified as a threatened species because of their similarity in appearance to the American Crocodile, which IS an endangered species.

Scientific Classification

phylum Chordata
subphylum Vertebrata
class Reptilia
order Crocodilia
family Alligatoridae
genus & species Alligator mississippiensis

Questions or comments about this page?

The Robinson Library >> Order Crocodilia

This page was last updated on August 13, 2018.