True crocodiles patrol tropics on four continents’ waters
True crocodiles (family Crocodylidae) are large semiaquatic reptiles of tropical Africa, Asia, the Americas, and Australia. Looser speech sometimes folds all living Crocodylia—including alligators and gharials—under the same everyday name. Eighteen living species range from a dwarf under two metres to a saltwater giant topping a tonne.
Crocodiles are the family Crocodylidae, named by Georges Cuvier in 1807 and placed in the order Crocodilia alongside alligators and gharials. All are semiaquatic, gathering in rivers, lakes and wetlands and sometimes in brackish or salt water, and all are carnivores that feed mainly on vertebrates such as fish, reptiles, birds and mammals. The word travelled from the Greek krokódilos, loosely 'pebble worm', through the Latin crocodilus used by Pliny the Elder.
An Aesop fable pairing a fox with a crocodile dates to the sixth century BC, and Herodotus puzzled over the word a century later. Medieval Latin produced variants such as cocodrillus, and English first uses the word in the early 14th-century verse romance Kyng Alisaunder. The German traveller Felix Fabri wrote of 'Cocodrillen' after his Holy Land journey of 1483.
Telling a crocodile from an alligator is mostly a matter of the head, since crocodiles tend to have narrower snouts, while the gharial's slender jaws make it the easiest of the three to pick out. DNA work has overturned older anatomical views by showing crocodiles are closer kin to gharials than to alligators. The family splits into two subfamilies, Crocodylinae with 13 to 14 living species and Osteolaeminae, for 18 recognised species in all, and a 2009 genetic study hinted at a further unnamed dwarf crocodile.
Sizes span the dwarf crocodile, whose adults reach only 1.5 to 1.9 metres, to the saltwater crocodile, which can pass 6 metres and 1,000 kilograms. The largest ever kept in captivity was Yai, a saltwater and Siamese hybrid at Thailand's Samutprakarn Crocodile Farm, 6 metres long and 1,200 kilograms, who lived from 1972 to 2025. A membrane anchors the tongue so it cannot be stuck out, and swimming crocodiles fold their feet against their flanks for speed.
Source: Crocodile
