Crocodiles or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia.
Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania and numerous smaller islands.
Reptiles are tetrapod animals in the class Reptilia, comprising today's turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, and their extinct relatives.
Africa is the world's second-largest and second-most-populous continent.
Crocodile Surprise Attacks Wildebeest | BBC Earth by BBC Earth
Crocodylinae, all of whose members are considered true crocodiles, is classified as a biological subfamily.
In biological classification, a subfamily is an auxiliary taxonomic rank, next below family but more inclusive than genus.
Alligator Vs Crocodile by What Lurks Below
A broader sense of the term crocodile, Crocodylidae that includes Tomistoma, is not used in this article.
The crocodylian family Crocodylidae includes the true crocodiles, which are the members of the subfamily Crocodylinae, as well as potentially the false gharial, the only extant member of the subfamily Tomistominae.
The false gharial, also known as Malayan gharial, Sunda gharial, and tomistoma, is a freshwater crocodilian native to Peninsular Malaysia, Borneo, Sumatra, and Java.
The term crocodile here applies to only the species within the subfamily of Crocodylinae.
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity.
The term is sometimes used even more loosely to include all extant members of the order Crocodilia, which includes the alligators and caimans, the gharial and false gharial, and all other living and fossil Crocodylomorpha.
The gharial, also known as the gavial, and fish-eating crocodile is a crocodilian in the family Gavialidae, native to sandy freshwater river banks in the plains of the northern part of the Indian subcontinent.
A caiman is a crocodilian alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within Alligatoridae, the other being alligators.
Crocodilia is an order of mostly large, predatory, semiaquatic archosaurian reptiles, known as crocodilians.
Although they appear similar, crocodiles, alligators and the gharial belong to separate biological families.
The gharial, with its narrow snout, is easier to distinguish, while morphological differences are more difficult to spot in crocodiles and alligators.
A snout is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw.
The most obvious external differences are visible in the head, with crocodiles having narrower and longer heads, with a more V-shaped than a U-shaped snout compared to alligators and caimans.
Another obvious trait is that the upper and lower jaws of the crocodiles are the same width, and the teeth in the lower jaw fall along the edge or outside the upper jaw when the mouth is closed; therefore, all teeth are visible, unlike an alligator, which possesses in the upper jaw small depressions into which the lower teeth fit.
A tooth is a hard, calcified structure found in the jaws of many vertebrates and used to break down food.
Also, when the crocodile's mouth is closed, the large fourth tooth in the lower jaw fits into a constriction in the upper jaw.
For hard-to-distinguish specimens, the protruding tooth is the most reliable feature to define the species' family.
Crocodiles have more webbing on the toes of the hind feet and can better tolerate saltwater due to specialized salt glands for filtering out salt, which are present, but non-functioning, in alligators.
Webbing is a strong fabric woven as a flat strip or tube of varying width and fibres, often used in place of rope.
The salt gland is an organ for excreting excess salts.
Another trait that separates crocodiles from other crocodilians is their much higher levels of aggression.
Aggression is overt or covert, often harmful, social interaction with the intention of inflicting damage or other unpleasantness upon another individual.
Crocodile size, morphology, behaviour and ecology differ somewhat among species.
Behavior or behaviour is the actions and mannerisms made by individuals, organisms, systems or artificial entities in conjunction with themselves or their environment, which includes the other systems or organisms around as well as the physical environment.
Ecology is the scientific analysis and study of interactions among organisms and their environment.
However, they have many similarities in these areas as well.
All crocodiles are semiaquatic and tend to congregate in freshwater habitats such as rivers, lakes, wetlands and sometimes in brackish water and saltwater.
Fresh water is naturally occurring water on Earth's surface in ice sheets, ice caps, glaciers, icebergs, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams.
A lake is an area filled with water, localized in a basin, that is surrounded by land, apart from any river or other outlet that serves to feed or drain the lake.
A wetland is a distinct ecosystem that is flooded by water, either permanently or seasonally, where oxygen-free processes prevail.
They are carnivorous animals, feeding mostly on vertebrates such as fish, reptiles, birds and mammals, and sometimes on invertebrates such as molluscs and crustaceans, depending on species and age.
Birds, also known as Aves, are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton.
Mammals are any vertebrates within the class Mammalia, a clade of endothermic amniotes distinguished from reptiles and birds by the possession of a neocortex, hair, three middle ear bones and mammary glands.
A carnivore, meaning "meat eater", is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging.
All crocodiles are tropical species that, unlike alligators, are very sensitive to cold.
Cold is the presence of low temperature, especially in the atmosphere.
They separated from other crocodilians during the Eocene epoch, about 55 million years ago.
The Eocene Epoch, lasting from 56 to 33.9 million years ago, is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era.
Many species are at the risk of extinction, some being classified as critically endangered.
A critically endangered species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild.
In biology and ecology, extinction is the end of an organism or of a group of organisms, normally a species.