They have membranes and fleshy valves which protect the eyes and close ears, nostrils, and trachea when they are underwater. The tail is laterally compressed, making alligators powerful swimmers. Alligators lay eggs and the females exhibit advanced parental care. Females build large nests of vegetation. The rotting material maintains a temperature of 86-89 degrees to incubate the eggs.
Incubation lasts approximately ten weeks.
The incubation temperature is what determines the sex of the offspring. After laying up to forty eggs the female remains near the nest. The young make a peeping noise after they hatch and this encourages the female to tear open the nest and help release the young. She may carry the hatchlings to water and she guards her young for the next few months. Young alligators grow about one foot per year for the first few years.