Alligators and their cousins are large reptiles in the order Crocodilia, which inhabit rivers, marshes and lakes in warmer climates throughout the world. These carnivores with powerful jaws survived the mass extinction that killed off dinosaurs, with about 23 species still in existence. Characterized by short legs and clawed, webbed feet, Crocodilians are built so their eyes, ears and nostrils stay above water while their bodies stay hidden beneath the water's surface.
The family Alligatoridae contains two subfamilies: true alligators and caimans. True alligators include the American alligator (A. mississippiensis) and the Chinese alligator (A. sinensis). American alligators live in freshwater rivers, lakes and swamps in the southeastern United States, while the Chinese alligator is found only in the Yangtze River basin. American alligators have a broader and rounder snout and are substantially larger than their Chinese cousins -- American males average 11 feet and females about 8 feet, while Chinese alligators average half that. Once near extinction, the American alligator made a successful comeback and was taken off the endangered list in 1987. The Chinese alligator is listed as critically endangered, with an estimated 150 left in the wild. Captive breeding programs are experimenting with re-stocking that population.
Three genera of the subfamily Caimaninae are also in the family Alligatoridae. Caimans are generally smaller and have narrower bodies than alligators, but the black caiman is the largest alligator and can grow to 20 feet. On the other end of the spectrum is Cuvier’s dwarf caiman, which averages less than 5 feet in length. Caimans inhabit Central and South America, along rivers, lakes, marshes and mangrove swamps.
True crocodiles, in the subfamily Crocodylinae, can be found in the tropics throughout the world. The 13 species vary in length from just over 3 feet to nearly 30 feet. Compared to its cousin, a croc’s snout is more slender and triangular, and two long teeth on the lower jaw are visible when its mouth is closed. Crocodiles are considered more aggressive than alligators. A small population lives in southern Florida, the only place where alligators and crocodiles live together.
The gharial, also know as the gavial, is in the family Gavialidae. This reptile has a very long and slender snout, with a characteristic bulbous growth on the tip. The largest males can reach more than 20 feet in length. They inhabit rivers of the Indian subcontinent but are close to extinction in the wild, with the largest populations on three tributaries of the Ganges. The International Union for Conservation of Nature lists gharials as critically endangered.
- Comstock Images/Comstock/Getty Images