Crocodiles and alligators belong to the same order of reptiles, the Crocodilia. This order has only 24 living species belonging to it, although it is related to the giant lizards of Jurassic times – creatures that existed some 150 million years ago. Other species belonging to this order are the caimans, found in Central and South America, and the thin-snouted, fish-eating gavials of northern India.
How do you tell the difference between crocodiles and alligators..?
Crocodiles and alligators look so alike that it is often very difficult to tell them apart when you see them in zoos. They both have tough, scaly skins and when they are lying in water, their nostrils, eyes and ears are on the same level. The answer is to wait until they appear on dry land, and then take a good look at their teeth. If you look carefully, you will find that crocodile teeth are more or less in line with each other, except for the fourth tooth on each side of the bottom jaw which is larger than the rest. When the crocodile closes its mouth, these two teeth fit into a notch on each side of the upper jaw so that you can see them.
Alligators, on the other hand, have all their top teeth outside their bottom teeth, so that when they close their mouths, no teeth can be seen.
How do crocodiles catch their prey..?
Crocodiles live in sluggish streams and lakes, often floating without movement for hours on end, so that an unwary creature might take them for dead. It would soon learn its mistake.
When a crocodile wants to move, it can move very fast indeed. Waiting a little way out from the shore, it will bide its time until, suddenly, swimming strongly and silently with vigorous movements of its flattened tail, it will seize its prey with a snap of its powerful jaws. Then it drags it to deeper water, where it will drown it and eat it.
Not all species of the Crocodilia are meat-eaters, however. The gavials of northern India, for example have long, thin snouts which are especially adapted to a fish-eating diet.
How do crocodiles find their mates...?
Crocodiles find each other during the mating season by using their sense of hearing and their sense of smell. When the mating season arrives, the males start calling for females with loud, intermittent bellows. These belows can be heard from a considerable distance.
Crocodiles also have two sets of special scent glands that are situated on the underside of the body. When the animal is basking in the sun, the scent glands come into contact with the soil and they secrete a strong, musky odour which leaves a trail that can be followed by other members of the species.
How do crocodiles build their nests..?
Crocodiles are egg-laying reptiles, and the first thing a female must do after she has mated is build a nest. Most species scoop up mud and plants in their jaws and build a mound of rotting vegetation. Then the female makes a hollow in the centre and lays anything from 20to 70 eggs in it. Afterwards, she covers them up and leaves them, but she does not stray far away.
The eggs are kept warm by the heat of the sun and the fermenting vegetable matter. When the young are ready to hatch, they make loud, hiccough- like noises which bring the mother to her nest.
She scratches the top of the nest away and the young break out of their shells. The young use their strong egg tooth, which has developed on the tip of the snout, to chip through the shell. This special tooth is lost soon after hatching. When a young crocodile is ready to hatch, it chips away at the shell with a special tooth it has only for this occasion.
American Alligators of 5 - 6 meters (16 - 20 feet) have been recorded in the past but today an adult male of 4 meters (13 feet) is considered large.
Juvenile Alligators are black with 10 - 11 narrow yellow crossbands on the tail and 4 - 5 on the body.
As they grow larger the crossbands fade and in adults, are rarely visible on the body. The eyes are normally silverish in color. The snout is moderately long and wide, generally uniform in width, with a bony nasal bridge. Some of the characteristics that vary among individuals are the presence or absence of bony plates or buttons (osteoderms) in the thoracic or ventral scales, the shape of the snout, and the massiveness of the skull.
Alligators are like other reptiles. They have scaly skin. They lay eggs with shells, and they are cold - blooded. Alligators can grow to be twelve or fourteen feet long and weigh from just a few pounds to more than 2,000 pounds. An eight - foot alligator is unusual in the wild.
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