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Definition: crocodile from Collins Dictionary of Biology

any large, tropical, aquatic lizardlike reptile of the order Crocodilia, possessing a four-chambered heart that is unique in reptiles.


Summary Article: crocodile
from The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide

Large scaly-skinned reptile with a long, low body and short legs. Crocodiles can grow up to 7 m/23 ft in length, and have long, powerful tails that propel them when swimming. They are found near swamps, lakes, and rivers in Asia, Africa, Australia, and Central America. They are fierce hunters and active mainly at night. Young crocodiles eat worms and insects, but as they mature they add frogs and small fish to their diet. Adult crocodiles will attack animals the size of antelopes and, occasionally, people. They can live up to 100 years and are related to the alligator and the smaller cayman.

Types of crocodile There are 15 species of crocodile, all of them endangered, found in tropical parts of Africa, Asia, Australia, and Central America. The largest is the saltwater (indopacific) crocodile Crocodylus porosus, which can grow to 7 m/23 ft or more, and is found in eastern India, Australia, and the western Pacific, in both freshwater and saltwater habitats. The Nile crocodile C. niloticus is found in Africa and reaches 6 m/20 ft. The American crocodile C. acutus, about 4.6 m/15 ft long, is found from southern Florida to Ecuador. The gavial, or gharial, Gavialis gangeticus is sometimes placed in a family of its own. It is an Indian species that grows to 6.5 m/21 ft or more, and has a very long narrow snout specialized for capturing and eating fish. The Cuban crocodile C. rhombifer has a short snout, grows up to 3.5 m/11.5 ft, and lives in freshwater swamps in Cuba. Morelet's crocodile C. moreletti is found in Central America, where it is overhunted, and grows up to 3.5 m/11.5 ft. Johnston's crocodile C. johnstoni is an Australian crocodile that feeds mainly on fish and reaches up to 3 m/9.75 ft in length. The Siamese crocodile C. siamensis is found in the wild in Cambodia and Laos. These populations consist of only a few hundred crocodile, making the Siamese one of the most endangered crocodile species. The Philippine crocodile C. mindorensis is found in the Philippine Islands and grows to just under 3 m/9.75 ft. C. palustris is an Indian crocodile resembling the Nile crocodile but smaller, reaching up to 4 m/13 ft. The Orinoco crocodile C. intermedius grows up to 6 m/19.5 ft. Tomistoma schlegelli is found in rivers in India and Indochina and grows up to 4 m/13 ft. The African slender-snouted crocodile C. cataphractus grows up to 4 m/13 ft and is found in western and central Africa. Osteolaemus tetraspis, the dwarf crocodile, reaches only 2 m/6.6 ft in length and is found in the tropical forests of west and central Africa. The New Guinea crocodile C. novaguineae reaches 7 m/23 ft in length.

Classification Crocodiles are in the phylum Chordata, subphylum Vertebrata, class Reptilia, subclass Archosauria, order Crocodilia. There are 13 species in the Crocodylidae family.

Behaviour In some species, the female lays over 100 hard-shelled eggs in holes or nest mounds of vegetation, which she guards until the eggs hatch, before carrying the hatchlings down to the water in her mouth. When in the sun, crocodiles cool themselves by opening their mouths wide, which also enables scavenging birds to pick their teeth. They can stay underwater for long periods, but must surface to breathe; their nostrils can be closed underwater and they ballast themselves with stones to adjust their buoyancy. Crocodiles have remained virtually unchanged for 200 million years.

Fossil crocodiles The fossil remains of an extinct plant-eating crocodile were discovered in 1995 near the Chang Jiang River in Hubei province, China. Named Chimaerasuchus paradoxus by its discoverers, it lived about 120 million years ago and its teeth were flattened for grinding plant material. A fossil crocodile Simosuchus was found in Madagascar in 2000, and was dated as having lived 70 million years ago, measuring 1.2 m/3.9 ft in length. It was concluded that the creature lived in a burrow and ate plants.

Differences between crocodiles and alligators Crocodiles differ from alligators in that they have a narrower, more pointed snout and their fourth tooth on the lower jaw can always be seen, even when their mouth is shut. On average, they are larger.

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