Crocodiles, also known as genuine crocodiles, are huge semiaquatic reptiles found in the tropics of Africa, Asia, the Americas, and Australia. Crocodylinae is a biological subfamily in which all species are regarded as genuine crocodiles. This article does not use the name crocodile in its broadest definition, Crocodylidae (which includes Tomistoma). Only the species of the Crocodylinae subfamily are referred to as crocodiles in this context. All current members of the order Crocodilia, which includes alligators and caimans (family Alligatoridae), gharials and false gharials (family Gavialidae), and all other living and fossil Crocodylomorpha, are referred to as Crocodilia.

Crocodiles, alligators, and the gharial are all members of distinct biological families, despite their resemblance. The gharial is simpler to recognize because of its short snout, whereas morphological distinctions in crocodiles and alligators are more difficult to spot. When compared to alligators and caimans, crocodiles have slimmer and longer skulls, as well as a V-shaped rather than a U-shaped snout. Another distinguishing feature of crocodiles is that their upper and lower jaws are the same width, and their lower jaw teeth fall along the edge or outside the upper jaw when the mouth is closed; thus, all teeth are visible, unlike an alligator, which has small depressions in the upper jaw into which the lower teeth fit. The fourth big tooth in the lower jaw also fits into a constriction in the upper jaw when the crocodile’s mouth is closed. The projecting tooth is the most dependable characteristic for determining the species’ family in difficult-to-distinguish specimens. Crocodiles have more webbing on their rear foot toes and can withstand saltwater better than alligators because they have specialized salt glands for filtering out salt, which is present but inactive in alligators. Crocodiles are also distinguished from other crocodilians by their significantly greater levels of aggressiveness.

Crocodiles vary in size, appearance, behavior, and ecology depending on the species. They do, however, have numerous commonalities in these areas. Crocodiles are semiaquatic animals that like to gather in freshwater environments, including rivers, lakes, and wetlands, as well as brackish and saltwater. They are carnivorous animals that eat vertebrates, including fish, reptiles, birds, and mammals, as well as invertebrates like mollusks and crabs, depending on their species and age. Crocodiles are all tropical species that, unlike alligators, are extremely cold tolerant. They split from other crocodilians some 55 million years ago, during the Eocene period. Many species are endangered, and some are designated as severely endangered.

The name crocodile is derived from the Ancient Greek krokódilos (o), which means ‘lizard,’ and is used in the phrase ho krokódilos tou potamo, which means “the lizard of the (Nile) river.” There are numerous other Greek spellings of the term, including the later version krokódeilos (), which is cited in several English dictionaries. Both krokodilos and krokodeilos would have been pronounced similarly in Roman Koine Greek, and any or both might have been the source of the Latinized version crocodlus employed by the ancient Romans.

Download Crocodile Silhouette PNG vector transparent background images