Crocodile

A crocodile (family) or true crocodile is a large, semiaquatic reptile that lives throughout the tropics in Africa, Asia, the Americas and Australia. These impressive animals are found in rivers, lakes, wetlands, and sometimes even in salty coastal waters. They are powerful predators, eating fish, reptiles, birds, mammals, and sometimes smaller creatures like molluscs and crustaceans.

Crocodiles are interesting because they have existed for millions of years, surviving many changes in the Earth’s history. Though they look similar to alligators and caimans, true crocodiles belong to a different family and are more sensitive to cold temperatures. Sadly, many crocodile species are now at risk of disappearing forever, with some listed as critically endangered. Protecting these ancient creatures and their habitats is very important for nature.

Etymology

The word crocodile comes from Middle English, borrowed from the Greek word krokódilos, meaning "stones worm." This word traveled through many languages over time. Ancient Greek writers like Herodotus talked about crocodiles, and the Romans, such as Pliny the Elder, also wrote about them. The word appeared in Old French and then made its way into English literature, showing how the idea of crocodiles spread through stories and books across different cultures.

Taxonomy and phylogeny

Phylogeny

Recent studies using DNA have shown that crocodiles are more closely related to gavialids than to alligators, which is different from what was thought before based only on looks. These studies help scientists understand how different crocodile groups are related to each other.

Species

Distribution of crocodiles

There are 18 different kinds of crocodiles living today. Scientists are still studying some crocodiles, especially those in the group called Osteolaemus, to learn more about them. If you are interested in the false gharial, which is not considered a true crocodile, you can read more about it here.

Species name	Distribution	Description/Comments
American crocodile (Crocodylus acutus)	Throughout the Caribbean Basin, including many of the Caribbean islands and South Florida.	A larger sized species, with a greyish colour and a prominent V-shaped snout. Prefers brackish water, but also inhabits lower stretches of rivers and true marine environments. This is one of the rare species that exhibits regular sea-going behaviour, which explains the great distribution throughout the Caribbean. It is also found in hypersaline lakes such as Lago Enriquillo, in the Dominican Republic, which has one of the largest populations of this species. Diet consists mostly of aquatic and terrestrial vertebrates. Classified as Vulnerable, but certain local populations under greater threat.
Hall's New Guinea crocodile (Crocodylus halli)	The island of New Guinea, south of the New Guinea Highlands	A smaller species that closely resembles and was long classified under the New Guinea crocodile, which it is now considered to be genetically distinct from. It lives south of the mountain barrier that divides the two species' ranges. It can be physically distinguished from the New Guinea crocodile by its shorter maxilla and enlarged postcranial elements. Cranial elements can still widely vary within the species, with populations from Lake Murray having much wider heads than those from the Aramia River.
Orinoco crocodile (Crocodylus intermedius)	Colombia and Venezuela	This is a large species with a relatively elongated snout and a pale tan coloration with scattered dark brown markings. Lives primarily in the Orinoco Basin. Despite having a rather narrow snout, preys on a wide variety of vertebrates, including large mammals. It is a Critically Endangered species.
Freshwater crocodile (Crocodylus johnstoni)	Northern Australia	A smaller species with a narrow and elongated snout. It has light brown coloration with darker bands on body and tail. Lives in rivers with considerable distance from the sea, to avoid confrontations with saltwater crocodiles. Feeds mostly on fish and other small vertebrates.
Philippine crocodile (Crocodylus mindorensis)	Endemic to the Philippines	This is a relatively small species with a rather broader snout. It has heavy dorsal armour and a golden-brown colour that darkens as the animal matures. Prefers freshwater habitats and feeds on a variety of small to medium sized vertebrates. This species is Critically Endangered and the most severely threatened species of crocodile.
Morelet's crocodile (Crocodylus moreletii)	Atlantic regions of Mexico, Belize and Guatemala	A small to medium sized crocodile with a rather broad snout. It has a dark greyish-brown colour and is found in mostly various freshwater habitats. Feeds on mammals, birds and reptiles. It is listed as Least Concern.
Nile crocodile (Crocodylus niloticus)	Sub-Saharan Africa	A large and aggressive species with a broad snout, especially in older animals. It has a dark bronze coloration and darkens as the animal matures. Lives in a variety of freshwater habitats but is also found in brackish water. It is an apex predator that is capable of taking a wide array of African vertebrates, including large ungulates and other predators. This species is listed as Least Concern.
New Guinea crocodile (Crocodylus novaeguineae)	The island of New Guinea, north of the New Guinea Highlands	A smaller species of crocodile with a grey-brown colour and dark brown to black markings on the tail. The young have a narrower V-shaped snout that becomes wider as the animal matures. Prefers freshwater habitats, even though is tolerant to salt water, in order to avoid competition and predation by the saltwater crocodile. This species feeds on small to mid-sized vertebrates.
Mugger crocodile (Crocodylus palustris)	The Indian subcontinent and surrounding countries	This is a modest sized crocodile with a very broad snout and an alligator-like appearance. It has dark-grey to brown coloration. Enlarged scutes around the neck make it a heavily armoured species. Prefers slow moving rivers, swamps and lakes. It can also be found in coastal swamps but avoids areas populated by saltwater crocodiles. Feeds on a wide array of vertebrates.
Saltwater crocodile (Crocodylus porosus)	Throughout Southeast Asia, Northern Australia and surrounding waters	The largest on average living reptile and most aggressive of all crocodiles. It is a big-headed species and has a relatively broad snout, especially when older. The coloration is pale yellow with black stripes when young but dark greenish-drab coloured as adults. Lives in brackish and marine environments as well as lower stretches of rivers. This species has the greatest distribution of all crocodiles. Tagged specimens showed long-distance marine travelling behaviour. It is the apex predator throughout its range and preys on virtually any animal within its reach. It is classified as Least Concern but with several populations under greater risk.
Borneo crocodile (Crocodylus raninus)	Island of Borneo in Southeast Asia	A freshwater species of crocodile that has been considered a synonym of the saltwater crocodile.
Cuban crocodile (Crocodylus rhombifer)	Found only in the Zapata Swamp and Isle of Youth of Cuba	It is a small but extremely aggressive species of crocodile that prefers freshwater swamps. The coloration is vibrant even as adults and the scales have a "pebbled" appearance. It is a relatively terrestrial species with agile locomotion on land, and sometimes displays terrestrial hunting. The snout is broad with a thick upper-jaw and large teeth. The unique characteristics and fossil record indicates a rather specialized diet in the past, preying on megafauna such as the giant sloth. This species sometimes displays pack-hunting behaviour, which might have been the key to hunting large species in the past, despite its small size. Today most prey are small to medium sized vertebrates. It is Critically Endangered, and the remaining wild population is under threat of hybridization.
Siamese crocodile (Crocodylus siamensis)	Indonesia, Brunei, East Malaysia and southern Indochina	A fairly small crocodile that prefers freshwater habitats. It has a relatively broad snout and olive-green to dark green coloration. It feeds on a variety of small to mid-sized vertebrates. Listed as Critically Endangered, but might be already extinct in the wild; status is unknown.
West African crocodile (Crocodylus suchus)	Western and Central Africa	Recent studies revealed that this is distinct species from the larger Nile crocodile. It has a slightly narrower snout and is much smaller compared to its larger cousin.
Osborn's dwarf crocodile (Osteolaemus osborni)	Western Africa	It is a heavily armoured species with uniform black coloration in adults, while juveniles have a lighter brown banding. Lives in the tropical forests of Western Africa. Feeds on small vertebrates and large aquatic invertebrates. It is a fairly terrestrial species and exhibits terrestrial hunting, especially at night.
Dwarf crocodile (Osteolaemus tetraspis)	Western Africa	It belongs to its own monotypic genus; however, new studies indicate there might be two or even three distinct species. It is a heavily armoured species with uniform black coloration in adults, while juveniles have a lighter brown banding. Lives in the tropical forests of Western Africa. Feeds on small vertebrates and large aquatic invertebrates. It is a fairly terrestrial species and exhibits terrestrial hunting, especially at night. This species is classified as Vulnerable.
West African slender-snouted crocodile (Mecistops cataphractus)	Western Africa	A medium sized species with a narrow and elongated snout. Lives in freshwater habitats within tropical forests of the continent. Feeds mostly on fish but also other small to medium sized vertebrates. It is a Critically Endangered species.
Central African slender-snouted crocodile (Mecistops leptorhynchus)	Central Africa	A medium sized species found in watery areas in dense rainforest. Feeds largely on fish. Insufficient conservation data, but was classified as Critically Endangered when lumped with M. cataphractus, although M. leptorhynchus is doing better in its home range.

Characteristics

Crocodiles are large reptiles that live in warm places around the world. They are strong swimmers with streamlined bodies and webbed feet, which help them move quickly in water. They have special skin on their backs made of thick, armored scales that protect them, and they can even absorb heat through this skin.

Crocodiles come in different sizes. Some, like the dwarf crocodile, are small, growing only about 1.5 meters long. Others, like the saltwater crocodile, can grow over 6 meters and weigh more than a ton! Most crocodiles start life very small, about 20 centimeters long, and grow bigger as they age, with males usually growing larger than females. Their teeth are also special because they can replace each tooth many times during their long lives.

Biology and behaviour

Crocodiles are closely related to birds and dinosaurs. Unlike most reptiles, they have a brain structure similar to mammals and a four-chambered heart. They also have special salt glands on their tongues, which help them live in salty water.

Crocodiles have excellent senses. They can see well in both bright and dim light, smell prey from far away, and hear sounds clearly. Their skin has special sensors that help them feel even the slightest ripple in the water, making them excellent hunters. They wait patiently for their prey and then strike quickly, using their powerful jaws to hold onto it. Their teeth are sharp but not great for tearing, which is why they often swallow large pieces whole. They can even digest bones thanks to their very acidic stomachs.

Relationship with humans

Danger to humans

Large crocodiles can be very dangerous to humans because they can strike very quickly, faster than a person can react. The saltwater crocodile and the Nile crocodile are the most dangerous, and they can harm many people each year in parts of Southeast Asia and Africa. Other species, like the mugger crocodile and the American crocodile, are also dangerous.

Crocodile products

Crocodiles are protected in many places, but they are also farmed for their hides, which are used to make leather goods such as shoes and handbags. Their meat is also eaten in some countries. Farming crocodiles has helped increase their numbers in some areas.

Crocodile hunting and conservation

Aboriginal Australians hunted crocodiles for many thousands of years in a way that did not harm the crocodile population. Later, commercial hunting increased, especially from the 1940s to the 1960s, when crocodiles were hunted for their skins. Laws were passed to protect crocodiles, and they have been a protected species since the 1970s. Their numbers have grown since then.

In religion and mythology

Further information: Crocodilia § Cultural depictions

Crocodiles have been important in many religions and myths around the world. In Ancient Egypt, there was a crocodile-headed god named Sobek. In Madagascar, some people believe crocodiles are ancestor spirits. In Hinduism, some gods and goddesses are shown riding crocodiles. In Indonesia, the city of Surabaya’s name is linked to a myth about a shark and a crocodile fighting.

In language and as symbols

The phrase “crocodile tears” describes pretending to cry or show emotion when you don’t really feel it. In schools, a line of children walking two by two is sometimes called a “crocodile.” In politics, the word “crocodile” can describe leaders or groups in different ways.