What is a Crocodilian?

Crocodilians are reptiles and have roamed the Earth since the time of the dinosaurs.

These reptiles are all semi-aquatic splitting their time between the land and water.

Each member of this order has a similar body shape with the head sitting in line with the body, four feet with partially webbed toes and a strong tail which helps with swimming.

Their head features eyes and nostrils which sit above the rest of the body which means they can breath and see while almost entirely submerged.

Across their body they have scales which are made of keratin (the same protein that forms human fingernails and hair). In many species these are studded with bony plates known as scutes. Each scale is shed individually.

Crocodilians will all reproduce by laying eggs on land.

The ears of crocodiles are covered by a flap which prevents the entry of water while underwater. A clear, third eyelid known as the nictitating membrane covers the eyes while underwater.

All crocodilians are carnivores with their food determined by size. Prey is swallowed whole. As a result of their slow metabolism they can go for long periods of time without eating any food.

As a reptile the crocodilians are all cold-blooded and reliant on the heat in the environment to warm themselves up. If they are too warm they will sit with their mouth open which helps to regulate their temperature.

Crocodilians have four chambers in their heart similar to birds and mammals compared to other reptiles which have three.



Types of Crocodilian

Crocodilians are divided in to three families. These are the crocodiles, alligators and caimans and the gharials. A total of 23 species have been recorded with the crocodilians being the most species diverse group.

One of the key differences within the three families is the shape of their snout. Crocodiles tend to have a longer v-shaped snout while the alligators and caimans have shorter, rounded U-shaped snouts. Gharials have an elongated, thin snout which ends with an enlarged, rounded end.

Alligators and crocodiles can further be differentiated as the fourth tooth on the lower jaw of an alligator fits in to a pit within the upper jaw while the mouth is closed and cannot be seen. In crocodiles this tooth remains visible.

Crocodiles (Crocodylidae)

14 Species

Crocodiles have a longer snout which narrows to a point at the tip. Their fourth tooth can be seen when the mouth is closed.

This group includes the largest crocodilian the saltwater crocodile which is found throughout Asia and Australia.

Learn more about many crocodile species by reading our fact files which can be accessed below.

Alligators and Caimans (Alligatoridae)

8 Species

american alligator

Alligators and caimans are found throughout North America, South America and Asia.

They have a short, broad snout with a rounded end. The fourth tooth in their jaw is covered up when the mouth is closed. As they do not have a gland for excreting salt these animals tend to be found almost entirely in freshwater habitats.

Learn more about many species in the alligator and caiman family by reading our fact files which can be accessed below.

Gharials (Gavialidae)

1 Species


The Gharial family includes only a single species by the same name which can be found in Asia. They are most notable for their long snout which in males ends with a rounded point. This is a conspicuous bulge made of cartilage and is known as ghara. Females find this attractive and it helps them to attract a mate.

Learn more about the gharial with our fact file which you can access using the button below in the fact file section.

Of the crocodilians the heaviest is the saltwater crocodile which measure up to 7m (23ft) long and may weigh up to 1,000 kg (2,200 pounds) while the smallest is the Cuvier's dwarf caiman which only reaches 1.5m (5ft) long.

They continue to grow throughout their whole life.

Crocodiles are long lived with one passing away at the age of 115.


Crocodilian Fact Files


Vancouver Aquarium. 2020. Crocodilians :: Vancouver Aquarium. [online] Available at: <https://www.vanaqua.org/education/aquafacts/crocodilians> [Accessed 31 December 2020].

2002. "Crocodylia" (On-line), Animal Diversity Web. Accessed December 31, 2020 at https://animaldiversity.org/accounts/Crocodylia/

Sydenham, Shirley. & Thomas, Ron. 2020. Crocodilians [online] www.kidcyber.com.au

Crocodilian.com. 2020. Crocodilian Species List: Crocodiles, Caimans, Alligators, Gharials. [online] Available at: <http://crocodilian.com/cnhc/csl.html> [Accessed 31 December 2020].

Animals.sandiegozoo.org. 2020. Crocodilian | San Diego Zoo Animals & Plants. [online] Available at: <https://animals.sandiegozoo.org/animals/crocodilian> [Accessed 31 December 2020].


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