Scientific name of snake is Serpentes. Snakes are legless animals with a thin, highly elongated body, devoid of mobile eyelids. They originated from lizards about 135 million years ago and became the last of the reptile groups that appeared on Earth.
The vast majority of lizards have limbs. Snakes do not have front legs, although rudiments of the hind legs are sometimes noticeable in the form of claws. With legless lizards, which look very similar to snakes, mobile eyelids. Snakes also differ in the features of the structure of the head and body, associated with their peculiar way of feeding.
Now in nature you can find species that are in the transition from lizard to snake. Such individuals have a snake’s body, but at the same time they still have limbs. Snakes refer to vertebrates. The length of the smallest snakes is only 12.5-15 cm with a mass of not more than 10-15 g. But the giants exceed in length 9 meters and weigh hundreds of kilograms, being actually the longest among modern terrestrial vertebrates, and the fossil species were twice as long as today. Opinions about the limiting sizes of snakes diverge.
Snakes along with fish, amphibians and other reptiles belong to cold-blooded (ectothermic) animals. This means that, unlike mammals and birds, they do not produce enough heat to maintain a constant body temperature. Therefore, snakes like to bask in the sun. However, they are poorly protected from overheating, which quickly kills them.
At least one kind of pythons can not be called completely cold-blooded, as the female is able to warm up the eggs a little, curled around them with a ring.