reptiles first appeared on Earth hundreds of millions of years ago.High organization allowed them to easily destroy invertebrate competitors, becoming the sole 'rulers'.From that time began their heyday.The dominance of reptiles on the planet has reached unimaginable proportions!They not only took all the land, but returned to the water, which significantly pushed the ancient fish, reigning there.Moreover, creeping up in the air!Today, reptiles - this is one of the most interesting, diverse and colorful group of animals on Earth.It is interesting that no one class of animals people are so contradictory as to reptiles: their love and hate at the same time, they cause nedetskiy interest and mystical horror.Externally, the reptiles can vary significantly.Next, we consider several types of buildings.
Yascherichny, snake and tortoise-shell type structure reptiles
Perhaps the most common structure of reptiles - the so-called yascherichny type.Individuals belonging to him have his head, cervical, itself the trunk, tail and four limbs.It lizards, crocodiles and tuatara.The next type of - a snake.Probably, it is not necessary to explain that the representatives of this appearance of the limbs speech just can not be!It is flexible, with an elongated torso, reptiles - snakes and lizards, many have lost their limbs.Representatives of the tortoise type of structure on all grounds fit yascherichnoe structure, but only with another feature - the body, concluded in a powerful shell.Of course, this cherepahi.A now let's talk about the signs that distinguish reptiles are not within their group, and, let's say, on the "world stage".
Clad in "armor»
main features of reptiles that distinguish them from other animals - is, of course, especially the movement of earth and leather "armor."On the first aspect, we have already spoken.Let's look at the second sign.The fact that powerful skin reptiles developed horny layer which forms the plates and scales.Almost all of the animal's body is covered with these "armor", even the eyelids and thin skin between the fingers!This leather "Mail" - a very strong defense, and shields, usually covering the top of the head - a kind of "hat."Sometimes the horny scutes grow bone plates.They protect the body armor like a reptile.That's interesting arranged crocodiles, lizards, snakes and other scaly terrestrial animals.But what to do with their flexibility?Is this "chain mail" does not allow them to even turn his head?Fortunately, it is not so!And why reptiles necessary mobility of the head?The ability to rotate the head plays an important role in hunting and security reptiles.We'll talk about this in more detail.
Why reptiles necessary mobility of the head
As is known, reptiles - a continuation of amphibians, left on dry land.One of the features that distinguish reptiles from amphibians - is the presence of a cervical department.For clarity, let's say that, for example, no frogs neck and head immediately goes into the body.The neck allows reptiles to turn his head to the side.You may ask, why reptiles necessary mobility of the head?Answering example sand lizard.On hearing a sound or rustle of a moving object, the lizard immediately turns his head towards him and sees everything that happens.If she is in danger - it gets away, but if it is a potential prey, the lizard catches it quite skillfully cracking down on it.The ability to rotate their heads in different directions makes reptiles flexible, almost imperceptible, as well as lightning hunters.That is why the reptiles require mobility of the head.
Interesting about snakes
Perhaps the most unique reptiles - snakes.They are adapted to crawl without the help of the limbs and swallow large prey whole.Snakes are fundamentally different from other reptiles is very long and flexible body, which, in turn, leads to a very peculiar arrangement of internal organs.As we know, in normal vertebrates, many organs are paired and arranged symmetrically.Snakes from them almost always only half, for example, many of them have only the right lung.And if there are paired organs, then they are at opposite ends of a long torso.For example, the right kidney is shifted to the head, the left - to the tail!When we hear the word "snake", involuntarily come to mind thoughts of poisonous reptiles.But today, science knows more than 2700 species of snakes, and only 700 of them - are poisonous.
