Crocodiles are large, carnivorous, amphibious reptiles belonging to the order Crocodylia. They possess powerful jaws with numerous conical teeth, short legs with clawed webbed toes, and thick, plated skin. Their unique body form allows them to keep their eyes, ears, and nostrils above the water surface while staying hidden. \ Crocodiles are living relatives of the dinosaur-like reptiles of prehistoric times and the nearest living relatives of birds. The order Crocodylia includes the "true crocodiles," alligators, caimans, and gavials. True crocodiles (family Crocodylidae) are found in tropical areas of Africa, Asia, Australia, and the Americas. They are primarily nocturnal predators that eat fish, mammals, and birds.

What is the order Crocodylia?

The reptile order Crocodylia includes generally large, amphibious animals with lizard-like appearances and carnivorous habits. Crocodiles possess powerful jaws with many conical teeth, short legs with clawed webbed toes, thick, plated skin, and a long, massive tail. The order Crocodylia consists of the "true crocodiles," alligators, caimans, and gavials. Differentiation of the families and genera of the order Crocodylia occurs via the anatomical peculiarities of their skulls. The classification of each species is based mainly upon external characteristics, such as the proportions of the snout, the bony structures on the dorsal side of the snout, the number of teeth, the number and arrangement of the large knobs on the nape of the neck, and the characteristics of the dorsal plates. The annotated classification of the order Crocodylia is: * Order Crocodylia, or Crocodilia: Archosaurs with a secondary palate; heavy cylindrical body; large, triangular head; legs short, toes webbed; long, muscular tail; large flat plates on belly, keeled ones on back; heart 4-chambered. * †Suborder Protosuchia: Upper Triassic; muzzle very short; choanae (internal nostrils) in region of palatine bones. * †Suborder Mesosuchia: Jurassic to Upper Cretaceous; choanae in posterior part of palatine bones. * †Suborder Sebecosuchia: Upper Cretaceous to Miocene; skull laterally flattened; choanae in depression in anterior part of pterygoids. * Suborder Eusuchia: Upper Jurassic to Recent; choanae entirely enclosed by pterygoids. * Family Alligatoridae (alligators and caimans): 4 genera and 8 species; teeth of lower jaw fit inside those of upper jaw. * Family Crocodylidae (true crocodiles): 3 genera and 17 species; teeth of upper and lower jaws form one interdigitating row when mouth is closed. * Family Gavialidae (gavial): 2 genera and 2 species; extremely long snout, more than 22 teeth in each jaw; nasal bones separated from premaxillaries.

What animals are included in the order Crocodylia?

The reptile order Crocodylia includes generally large, amphibious animals with lizard-like appearances and carnivorous habits. Crocodiles are a living link to prehistoric dinosaur-like reptiles and the nearest living relatives to birds. The order Crocodylia includes the families Alligatoridae, Crocodylidae, and Gavialidae:

How are crocodiles different from alligators and caimans?

Crocodiles, alligators, and caimans, all belonging to the reptile order Crocodylia , share similarities such as long snouts, powerful tails, short legs, and bony-plated backs. However, key differences exist. Crocodiles have narrow, V-shaped snouts, while alligators possess broad, U-shaped snouts. When a crocodile closes its mouth, the large fourth tooth on each side of its lower jaw projects outside the snout. In contrast, an alligator's lower teeth are typically not visible when the mouth is shut. Color-wise, crocodiles tend to be olive or tan, whereas alligators are often gray or black. Crocodiles are also generally more aggressive and favor saltwater habitats, while alligators prefer freshwater environments. Caimans are related to alligators and live in Central and South America.

Where do members of Crocodylia live, and what types of habitats do they prefer?

Members of the reptile order Crocodylia live mainly in the humid, lowland tropics of both the Northern and Southern hemispheres. They inhabit swamps, lakes, and rivers, though some species will venture into brackish water or the sea. The estuarine crocodile and the American crocodile can live in marine waters, though they normally occupy brackish and freshwater habitats. The smooth-fronted caiman prefers rocky, fast-flowing rivers, while the dwarf crocodile is mainly found in the rivers of forest regions. The gharial inhabits the rivers of northern India and Nepal.

How have crocodiles and their relatives adapted to their environments over time?

Crocodiles, belonging to the reptile order Crocodylia , have evolved several adaptations for their amphibious lifestyle. Their elongated body and muscular tail facilitate rapid swimming. The placement of their eyes, ears, and nostrils on the upper part of their head allows them to stay submerged while still sensing their surroundings. To regulate body temperature, crocodiles engage in behavioral strategies such as sunning themselves and seeking shade or cooler waters. They also possess glands in the tongue that help excrete excess salt, allowing them to inhabit both freshwater and marine environments. Some species dig burrows for refuge from drought or cold.

crocodile

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Images & Videos

Illustration of an estuarine or saltwater crocodile (Crocodylus porosus) with its mouth open, showing scaly skin and powerful limbs, alongside a scale bar for size reference.

Illustration of a Mississippi or American alligator (Alligator mississippiensis) with its mouth open, showing a broad snout, armored body, and thick tail, alongside a scale bar for size reference.

Nile crocodile (Crocodylus niloticus) with mouth wide open, displaying sharp teeth, lies on a muddy riverbank in sunlight at Pilanesberg National Park.

estuarine crocodile, or saltwater crocodile (Crocodylus porosus)

Close-up of two green gharials crocodiles, or the scientifc name Gavialis gangeticus, resting in shallow water, showing their long, narrow snouts and textured greenish skin.

American alligator (Alligator mississippiensis)

A Chinese alligator (Alligator sinensis) rests on sandy ground near a concrete wall, its body stretched out with head slightly raised.

Witness a crocodile hatchling emerge from its egg and call for its mother

At a Glance

crocodile summary

crocodile

reptile order, Crocodylia

Also known as: Crocodilia, Crocodylia, crocodilian

Written by

James P. RossAll

Fact-checked by

Britannica Editors

History

Top Questions

What are crocodiles?
Crocodiles are large, carnivorous, amphibious reptiles belonging to the order Crocodylia. They possess powerful jaws with numerous conical teeth, short legs with clawed webbed toes, and thick, plated skin. Their unique body form allows them to keep their eyes, ears, and nostrils above the water surface while staying hidden.

\
Crocodiles are living relatives of the dinosaur-like reptiles of prehistoric times and the nearest living relatives of birds. The order Crocodylia includes the "true crocodiles," alligators, caimans, and gavials. True crocodiles (family Crocodylidae) are found in tropical areas of Africa, Asia, Australia, and the Americas. They are primarily nocturnal predators that eat fish, mammals, and birds.
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1. What’s the Difference Between Alligators and Crocodiles?
2. crocodile
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What is the order Crocodylia?
The reptile order Crocodylia includes generally large, amphibious animals with lizard-like appearances and carnivorous habits. Crocodiles possess powerful jaws with many conical teeth, short legs with clawed webbed toes, thick, plated skin, and a long, massive tail.

The order Crocodylia consists of the "true crocodiles," alligators, caimans, and gavials. Differentiation of the families and genera of the order Crocodylia occurs via the anatomical peculiarities of their skulls. The classification of each species is based mainly upon external characteristics, such as the proportions of the snout, the bony structures on the dorsal side of the snout, the number of teeth, the number and arrangement of the large knobs on the nape of the neck, and the characteristics of the dorsal plates.

The annotated classification of the order Crocodylia is:
* Order Crocodylia, or Crocodilia: Archosaurs with a secondary palate; heavy cylindrical body; large, triangular head; legs short, toes webbed; long, muscular tail; large flat plates on belly, keeled ones on back; heart 4-chambered.
* †Suborder Protosuchia: Upper Triassic; muzzle very short; choanae (internal nostrils) in region of palatine bones.
* †Suborder Mesosuchia: Jurassic to Upper Cretaceous; choanae in posterior part of palatine bones.
* †Suborder Sebecosuchia: Upper Cretaceous to Miocene; skull laterally flattened; choanae in depression in anterior part of pterygoids.
* Suborder Eusuchia: Upper Jurassic to Recent; choanae entirely enclosed by pterygoids.
* Family Alligatoridae (alligators and caimans): 4 genera and 8 species; teeth of lower jaw fit inside those of upper jaw.
* Family Crocodylidae (true crocodiles): 3 genera and 17 species; teeth of upper and lower jaws form one interdigitating row when mouth is closed.
* Family Gavialidae (gavial): 2 genera and 2 species; extremely long snout, more than 22 teeth in each jaw; nasal bones separated from premaxillaries.
1 Britannica Source
1. crocodile
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What animals are included in the order Crocodylia?
The reptile order Crocodylia includes generally large, amphibious animals with lizard-like appearances and carnivorous habits. Crocodiles are a living link to prehistoric dinosaur-like reptiles and the nearest living relatives to birds.

The order Crocodylia includes the families Alligatoridae, Crocodylidae, and Gavialidae:
- Alligatoridae This family includes alligators and caimans.
- Crocodylidae This family includes the "true crocodiles".
- Gavialidae This family includes gavials.
1 Britannica Source
1. crocodile
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How are crocodiles different from alligators and caimans?
Crocodiles, alligators, and caimans, all belonging to the reptile order Crocodylia, share similarities such as long snouts, powerful tails, short legs, and bony-plated backs.

However, key differences exist. Crocodiles have narrow, V-shaped snouts, while alligators possess broad, U-shaped snouts. When a crocodile closes its mouth, the large fourth tooth on each side of its lower jaw projects outside the snout. In contrast, an alligator's lower teeth are typically not visible when the mouth is shut. Color-wise, crocodiles tend to be olive or tan, whereas alligators are often gray or black. Crocodiles are also generally more aggressive and favor saltwater habitats, while alligators prefer freshwater environments.

Caimans are related to alligators and live in Central and South America.
4 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Where do members of Crocodylia live, and what types of habitats do they prefer?
Members of the reptile order Crocodylia live mainly in the humid, lowland tropics of both the Northern and Southern hemispheres. They inhabit swamps, lakes, and rivers, though some species will venture into brackish water or the sea.

The estuarine crocodile and the American crocodile can live in marine waters, though they normally occupy brackish and freshwater habitats. The smooth-fronted caiman prefers rocky, fast-flowing rivers, while the dwarf crocodile is mainly found in the rivers of forest regions. The gharial inhabits the rivers of northern India and Nepal.
5 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How have crocodiles and their relatives adapted to their environments over time?
Crocodiles, belonging to the reptile order Crocodylia, have evolved several adaptations for their amphibious lifestyle. Their elongated body and muscular tail facilitate rapid swimming. The placement of their eyes, ears, and nostrils on the upper part of their head allows them to stay submerged while still sensing their surroundings.

To regulate body temperature, crocodiles engage in behavioral strategies such as sunning themselves and seeking shade or cooler waters. They also possess glands in the tongue that help excrete excess salt, allowing them to inhabit both freshwater and marine environments. Some species dig burrows for refuge from drought or cold.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

crocodile, (order Crocodylia, or Crocodilia), any of about 27 species of generally large, ponderous, amphibious animals of lizard-like appearance and carnivorous habit belonging to the reptile order Crocodylia. Crocodiles have powerful jaws with many conical teeth and short legs with clawed webbed toes. They share a unique body form that allows the eyes, ears, and nostrils to be above the water surface while most of the animal is hidden below. The tail is long and massive, and the skin is thick and plated.

Crocodiles are a living link with the dinosaur-like reptiles of prehistoric times and are the nearest living relatives of the birds. A large variety of crocodilian fossils have been discovered that date back 200 million years to the Late Triassic Epoch. Fossil evidence also suggests that three major radiations occurred. Only one of the four suborders of crocodiles has survived to modern times. The order Crocodylia includes the “true crocodiles,” alligators, caimans, and gavials.

General features

Size range and diversity of structure

Crocodiles are the largest and the heaviest of present-day reptiles. The largest representatives, the Nile crocodile (Crocodylus niloticus) of Africa and the estuarine (or saltwater) crocodile (C. porosus) of Southeast Asia and Australia, attain lengths of up to 7 meters (about 23 feet) and weigh more than 1,200 kg (nearly 2,650 pounds). Some fossil forms (such as Deinosuchus and Sarcosuchus) may have been between 10 and 12 meters (33 and 40 feet) long. In comparison, the smallest species, the smooth-fronted caiman (Paleosuchus) and the dwarf crocodile (Osteolaemus tetraspis), reach about 1.7 meters (about 6 feet) in length as adults.

All crocodiles have a relatively long snout, or muzzle, which varies considerably in shape and proportion. The scales that cover most of the body generally are arranged in a regular pattern, and thick, bony plates occur on the back. Families and genera are primarily distinguished by differences in skull anatomy. Species are identified principally by the proportions of the snout; by the bony structures on the dorsal, or upper, surface of the snout; and by the number and the arrangement of the scales.

Distribution and abundance

Crocodiles are found mainly in the lowland, humid tropics of the Northern and Southern hemispheres. The “true crocodiles” (family Crocodylidae) occur in most of Africa south of the Sahara, Madagascar, India, Sri Lanka, Southeast Asia, the East Indies, northern Australia, Mexico and Central America, the West Indies, and northern South America. In the family Alligatoridae, most caimans are confined to the tropical areas of Central and South America, though the ranges of the broad-snouted caiman (Caiman latirostris) and Jacaré caiman (C. yacare) extend into temperate areas of South America. The American alligator (Alligator mississippiensis) and the Chinese alligator (A. sinensis) also occur in temperate regions. In the family Gavialidae, the gavial (or gharial [Gavialis gangeticus]) is found in Pakistan, northern India, Nepal, Bhutan, Bangladesh, and Myanmar, whereas the false gharial (or false gavial [Tomistoma schlegelii]) inhabits freshwater habitats in Sumatra, Java, and Borneo and in Peninsular Malaysia.

Sea otter (Enhydra lutris), also called great sea otter, rare, completely marine otter of the northern Pacific, usually found in kelp beds. Floats on back. Looks like sea otter laughing. saltwater otters

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Throughout their range, crocodile populations have declined as human occupation and land use change has reduced their habitat. Many crocodilian species have been greatly depleted by overhunting for their valuable skins—which provide leather for handbags, shoes, belts, and other articles. Local use of crocodiles for meat and medicines is also widespread. People living near crocodiles often dislike them because the animals can become entangled in fishnets, prey on pets and livestock, and occasionally kill people.

Since about 1970 improved national protection, habitat conservation, and international regulation of trade have allowed many populations to recover. About half of the 27 species remain widespread and numerous with little chance of extinction. According to the International Union for Conservation of Nature and Natural Resources (IUCN), several species (the Chinese alligator [A. sinensis], the Cuban crocodile [Crocodylus rhombifer], the Orinoco crocodile [C. intermedius], the Philippine crocodile [C. mindorensis], the Siamese crocodile [C. siamensis], the slender-snouted crocodile [Mecistops cataphractus], and the gavial [G. gangeticus]) are critically endangered or (in the case of the false gharial [T. schlegelii]) endangered and face extinction if human pressures on their habitat are not relieved.

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Sustainable harvesting, regulated trade, and education have become valuable components of crocodilian conservation. Worldwide, various programs exist to provide incentives and economic benefits to communities that conserve habitat. For example, some communities in the Philippines are paid for each egg made safe from collectors or those intent on destroying nests. Crocodilian conservation has become a model for sustainable resource use. Commercial production by captive breeding, the collection of excess eggs from the wild, and regulated hunting yield 800,000–1,000,000 legal skins each year to international markets.

crocodile

General features

Size range and diversity of structure

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Distribution and abundance