Crocodiles

The gavial or gharial (family Gavialidae) is a single species, Gavialus gangeticus, which lives in a number of The endangered false gavial (Tomistoma schlegelii.). Photograph by A. Cosmos Blank. The National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission. sluggish, tropical rivers in India, Bangladesh, and Indochina. Gavials have a long, slender snout, and are almost exclusively fish eaters, catching their prey with sideways sweeps of the open-mouthed head. Gavials can attain a length of about 20 ft (6 m). Gavials are considered holy in the Hindu religion, and this has afforded these animals a measure of protection in India. Unfortunately, this is not sufficiently the case anymore, and gavials have become severely endangered as a result of overhunting for their hide.

The true crocodiles (family Crocodylidae) include about 16 species that live in tropical waters. Crocodiles are large, stout animals, with a much heavier snout than that of the gavial. The main food of crocodiles is fish, but some species can catch and subdue large mammals that venture close to their aquatic habitat, or attempt to cross rivers in which the crocodiles are living. Perhaps the most famous species is the Nile crocodile (Crocodylus niloticus) of Africa, which can grow to a length of 23 ft (7 m). This crocodile can be a predator of unwary humans, although its reputation in this respect far exceeds the actual risks, except in certain places. This species used to be very abundant and widespread in Africa, but unregulated hunting and, to a lesser degree, habitat loss, have greatly reduced its population.

The most dangerous crocodilian to humans is the estuarine or salt-marsh crocodile (Crocodylus porosus), which lives in salt and brackish waters from northern Australia and New Guinea, through most of Southeast Asia, to southern India. This species can achieve a length of more than 23 ft (7 m). Individuals of this crocodile species sometimes occur well out to sea.

Other species are the mugger crocodile (Crocodylus palustris) of India, Bangladesh, and Ceylon; the Australian crocodile (C. johnsoni) of northern Australia; and the New Guinea crocodile (C. novaeguineae) of New Guinea and parts of the Philippines.

The American crocodile (Crocodylus acutus) is a rare and endangered species of brackish estuaries in southern Florida, occurring more widely in central and northwestern South America and the Caribbean. This species can achieve a length of 20 ft (6 m). The Orinoco crocodile (C. intermedius) occurs in the Orinoco and Amazon Rivers of South America.

The false gavial (Tomistoma schlegelii) is a slender-snouted species of Southeast Asia.

The alligators and caimans (family Alligatoridae) are seven species that occur in fresh water, with a broader head and more rounded snout than crocodiles. The American alligator (Alligator mississipiensis) can achieve a length of 13 ft (4 m), and occurs in the southeastern United States as far north as South Carolina and Alabama. This species was endangered by unregulated hunting for its hide. However, strict conservation measures have allowed for a substantial recovery of the species, and it is now the subject of a regulated hunt.

The Chinese alligator (Alligator sinensis) occurs in the lower reaches of the Yangtze and Kiang Rivers in southern China, and it is the only member of its family to occur outside of the Americas. The Chinese alligator can grow as long as 6.5 ft (2 m).

Caimans are animals of freshwater habitat in South and Central America. The black caiman (Melanosuchus niger) can achieve a length of 16 ft (5 m). The spectacled caiman (Caiman crocodilus) and the broad-nosed caiman (C. latisrostris) of eastern Brazil can both grow somewhat longer than 6.5 ft (2 m). The dwarf caiman (Paleosuchus palpebrosus) and the smooth-fronted caiman (P. trigonatus) live in more swiftly flowing streams and rivers and are relatively small species that do not exceed about 5 ft (1.5 m) in length.