Crocodilians

The crocodile, or crocodilian, family is divided into 3 groups:

crocodiles,
alligators & caimans,
gharials or gavials.

Crocodilians are reptiles, and are found in hot tropical areas of the world.

Crocodiles
Crocodiles have longer, narrower snouts than alligators, and the 4th tooth of the lower jaw is outside when the mouth is closed.

Some kinds of crocodile live in salt water and others live in fresh water.

Unlike other reptiles, crocodiles have four sections in their hearts, like mammals and birds have. Their long, flattened tail moves from side to side and propels them through the water, with their legs by their sides. This movement is helped by two ridges of upright scales along the tail. Their movement in the water is powered by their tail.

The legs are short with webbed toes, five on the front legs and four on the back legs. On land, crocodiles can run very quickly, lifting their bodies up off the ground. The eyes and nostrils are on the top part of the head so that they can lie in the water almost completely hidden from view.

Feeding
Crocodiles have very strong jaws, so strong that when they bite down to grab food, there is a loud sound. They do not chew their food. They swallow it in large chunks. In the stomach the food is broken down. They feed on a large variety of prey such as small mammals, birds and even domestic livestock. Crocodiles grab their prey and roll over in the water to drown the animal. They can leap high out of the water to reach their prey if necessary.

Life Cycle
After mating, the female crocodile lays about 50-80 eggs in a nest she makes near a river bank. She covers the nest with leaves and other vegetation. The rotting vegetation keeps the eggs warm and the nest moist. The female stays and guards the nest for 90 days until the eggs hatch. The hatching babies call out and their mother opens up the nest and carries the babies to the water, where they immediately start feeding on crabs, shrimps and insects. About half will not survive the first year.

Farming
In many places there are crocodile farms which breed crocodiles for meat and leather.

Crocodile 'Did you know?'

Crocodiles keep their body temperature steady by basking in the sun when the weather is cool, and by resting in the shade when it is hot. The temperature inside the nest of several kinds of crocodilians decides the sex of the young. If the nest temperature is 30ºC, mostly females will hatch from all the eggs, and if the temperature is above 34ºC, there will be mostly males. If the temperature is in between, there will be young of both sexes. Crocodiles have complicated behaviour patterns, including socialisation, hierarchies (social order), different vocal sounds, and mothers taking good care of their young. The oldest known crocodile was 115 years old when it died in a Russian zoo in 1997. There are about 23 species, or kinds, of crocodilians. Today, 18 of those 23 species are no longer endangered. The other 5 are critically endangered, and are, in order: the Chinese alligator, Philippine crocodile, Siamese crocodile, tomistoma (SE Asia) and Orinoco crocodile.

Some of the world's crocodiles:

SPECIES & SIZE	FOUND	SALT / FRESH WATER	COMMENTS
Nile crocodile, approx 4 -5 metres	central & southern Africa Madagascar	freshwater	Known to attack people & will attack boats
Estuarine crocodile, 4 to 7 metres	northern Australia, southeast Asia	saltwater, but survives in freshwater rivers far from the sea	The most dangerous of the crocodiles, the largest and heaviest
American crocodile, up to 7 metres	central America, Mexico,Colombia, Equador, parts of Florida	freshwater	Not known to attack people, however it is still dangerous
Johnson's crocodile, up to 3 metres	only in northern Australia	freshwater	Not known to attack people, but still regarded as dangerous.
Marsh crocodile, up to 4 metres	India and Sri Lanka	freshwater	Known to attack people, but more commonly feeds on small mammals

Go here for a colouring book of crocodile pictures http://www.nationalgeographic.com/coloringbook/crocodiles.html

Go here to find out about alligators and caymans, and gharials.

Acknowledge this source in your bibliography like this:
Sydenham & Thomas,Crocodilians. [Online] www.kidcyber.com.au (2000)