The first reptiles appeared on Earth several hundred million years ago. High organization allowed them to easily destroy invertebrate competitors, becoming the sole "rulers". From that time their heyday began. The reign of reptiles on our planet has reached unthinkable proportions! They not only captured all the land, but also returned to the water, where they significantly crowded out the ancient fish reigning there. Moreover, the reptiles rose into the air! Today, reptiles are one of the most interesting, diverse and vibrant groups of animals on planet Earth.
It is interesting that people do not relate to any class of animals as contradictory as reptiles: they are loved and hated at the same time, they cause non-childish interest and mystical horror. Externally, reptiles can vary significantly. Next, we consider several types of their structure.
Lizard, snake and tortoiseshell reptile types
Perhaps the most common reptile structure is the so-called lizard type. The individuals related to it have a head, a cervical spine, a trunk itself, a tail and four limbs. These are lizards, crocodiles, hatteria. The next type is snake. Probably, it’s not worth explaining that representatives of such an appearance simply can’t talk about limbs! These are flexible, with an elongated body, reptiles - snakes and many lizards that have lost their limbs. Representatives of the tortoise-type structure in all respects are suitable for a lizard structure, but with only one more feature - a body enclosed in a powerful shell. Of course, these are turtles.
And now let's talk about the signs that distinguish reptiles not within their group, but, let’s say, on the “world stage”.
Armored
The main signs of reptiles that distinguish them from other animals are, of course, the peculiarities of movement on the ground and leather "armor". We have already talked about the first feature. Let's look at the second symptom. The fact is that a powerful stratum corneum, which forms shields and scales, is developed in the skin of reptiles. Almost the entire body of the animal is covered with these “armor”, even the eyelids and thin skin between the fingers! Such leather “chain mail” is a very strong protection, and the shields, usually covering the upper part of the head, are a kind of “helmet”. Bone plates sometimes grow under the horny scutes. They, like armor, protect the body of a reptile.
Crocodiles, lizards, snakes and other scaly land animals are so interestingly arranged. But what about their flexibility? Is this "chain mail" does not give them the opportunity to even turn their heads? Fortunately, this is not so! Why do reptiles need head mobility? The ability to turn your head plays a big role in hunting and reptile safety. Let's talk about this in more detail.
Why reptiles need head mobility
As you know, reptiles are a continuation of amphibians that have come on land. One of the features that distinguish reptiles from amphibians is the presence of the cervical spine. For clarity, we say that, for example, frogs have no neck, and the head immediately goes into the body. The neck allows the reptile to turn its head to the side. You may ask why reptiles need head mobility? We answer with the example of a fast lizard. Having heard some sound or the rustle of a moving object, the lizard instantly turns its head in his direction and sees everything that happens. If she is in danger, she will flee; if it is potential prey, then the lizard grabs it, rather skillfully dealing with it. The ability to turn your head in different directions makes reptiles flexible, almost elusive, and also lightning-fast hunters. This is why reptiles need head mobility.
Interesting about snakes
Perhaps the most unique reptiles are snakes. They are adapted to crawl without the aid of limbs and swallow large prey whole. Snakes radically differ from other reptiles in a very long and elastic body, which, in turn, leads to a very peculiar arrangement of internal organs.
As we know, in ordinary vertebrates, many organs are paired and arranged symmetrically. Snakes almost always have only half of them left, for example, many of them have only the right lung. And if there are paired organs, then they are located at different ends of the long body. For example, the right kidney is shifted to the head, the left - to the tail! When we hear the word "snake", then involuntarily thoughts come to mind about a poisonous reptile. But today, science knows more than 2700 species of snakes, and only 700 of them are poisonous.
