Crocodilians are the closest surviving relatives of the great dinosaurs. They have changed very little during the 150 million years that they have lived on Earth.

Adaptations for a life in water

Crocodilians can move about on land - with surprising speed, particularly when alarmed or angry - but their bodies are mainly adapted for a life in water. The nostrils, eyes and ears lie along the top of the head so that the animal can hear, see, smell and breathe when the rest of the body is submerged.

When completely under the water, the ears are covered by small flaps of skin which can be closed to make the ears watertight. The nostrils can also be closed by special muscles, and the eyes have a 'third eyelid' which gives protection when diving.

There are special bony flaps in the throat which allow a crocodile to eat when submerged or breathe when its jaws are open underwater.

Crocodilians, being cold-blooded reptiles, have to avoid extremes of temperature. When it is fairly cool, they rest on a waterside bank, allowing the sun to warm their body. During the hottest part of the day, the animals will move into the shade or water to prevent their body from overheating.

Read More: The Nile Crocodile

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