Turtle isn’t a mammal, it’s reptile. It belongs to the class Reptiles (Reptilians), to the subclass Anapsida, and these are the oldest reptiles, which appeared 200 million years ago and were mostly extinct, the Turtle group, in which there are five suborders and eleven families.
And their species somewhere, if not yet discovered new, which is unlikely – about 210. So the turtles are very ancient creatures, contemporaries of the dinosaurs. And among them were giants the size of a small tank – for example, archelon.
Turtles have a hard shell. If the animal lacks calcium and falls ill with rickets, the shell can become soft, squeezing while doing so. This, in turn, can lead to the death of the turtle. Also there is a kind of elastic turtles, whose shell is soft enough. This feature, oddly enough, helps protect against predators. After all, such turtles hide from enemies in the crevices of stones, “inflating” there the shell and hopelessly getting stuck for a predator.
Turtles are amphibians. Some may find it strange to have a relationship with other amphibians, but this is a fact. Her relatives really are reptiles and reptiles, such as a lizard, a crocodile and a snake.
The tortoise can at any time free itself from the shell. This is possible only if the animal’s body itself falls out of the shell. But this will mean that the turtle is actually a half-decayed corpse. After all, its carapace is essentially a fused bones of the ribs and spine. The appearance of it, by the way, markedly changed the structure of internal organs. Muscles of the body atrophied, but the legs and neck became noticeably stronger.