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Reptiles
What are they?
It is an animal, with dry skin, breathes by lungs and are cold blooded. The skin must be scaly. There are a bit less than 7000 reptiles, including snakes, lizards, tuatara ( an ancient animal ). Due to the fact that they are cold blooded, they must avoid extreme heat and cold, so as not to become fried lizard ( well, I exaggerate ). Most avoid such situations by moving from sunny places to shady places and back to sunny places. In some parts, they come out at night ( in the hot regions ). Some hibernate too.
How do they live?
The size of a reptile varies.
A python can grow to 10 metres and a turtle ( leatherback
) can weigh 1 ton. Some, though, weigh much less and
are smaller.
Reptiles live everywhere, except the poles. Most are in the tropics. Some
yearn for deserts. Some like the wooded jungles. Some are prepared to place
all they have at stake, to live in water.
Though some reptiles are harmful, most do nothing much Most, even snakes,
avoid humans. Though some croc's kill humans ( how encouraging ), not all do.
Division of reptiles
There are four groups of reptiles -
These animals are useful too. Some eat them. Some are hunted for skins, some
for buttons ( tiny turtle shells ).
For the most part, the first group make up the largest of the reptiles. They account for around 5000 species of reptiles. Most lizards has legs ( namely 4 ), long tails, movable eyelids, external ear openings.
Snakes are a varied group, some poisonous ( that had to be the first point ), they have no legs, no eyelids, no ear openings. Snakes live in warm regions.
Turtles are those with shells and can contract themselves into it.
Crocodiles include alligators too. They have long snout, big strong jaws ( with big strong sharp teeth ), webbed hind legs. They use there tail to swim.
The tuatara is a inhabitant of several islands, and is not that well known. Though they look like lizards, they are more close related to extinct dinosaurs.
Their bodies.
Reptiles have some common features ( that's why they are all reptiles ). They are cold blooded, have a similar skin and some other common stuff.
The skin of a reptile is made up of scales. Snakes, lizards have overlapping scales. The scales of the other groups are individual and are called plates. The scales act as a protective cover. The skin of such reptiles serves as protective armour. Many species shed their skins, growing more scales, loosening the outer one. The snake pushes the skin backwards, and crawls out of it.
Poisonous reptiles have poison glands in their mouth. The venom attacks the nervous / circulatory system.
Most of the reptiles have good vision. They generally hear low pitched sounds. Snakes though hear by vibrations in the ground.
From where did they evolve and when?
See our page on reptile evolution
