The alligator is a large lizard-shaped reptile with four short legs and widespread toes, five on each front foot and four on the hind feet. The three inner toes on the front and back feet are clawed and the hind toes are webbed. The hide is rough and scaled and the tail is long and muscular.
Young alligators are black above, with bright stripes and blotches of yellow.
The belly is cream colored. In the adult these yellow markings disappear so that the back becomes uniformly dark, although the underparts remain light colored. Both male and female alligators are the same color, and there is no way to tell the two apart on the outside. The skin on the alligator is very tough and covered with smooth horny scales in rows. The head of the alligator is large, flat, elongated and equipped with enormous jaws, hinged far back so that the mouth opens wide.