The mollusks

The mollusks are the first representatives that we will see of the celomados, that is to say, the animals with a general cavity of the body draped by mesodermal fabric. It is a group that has reached a great evolutionary success. It is a question of animals of bilateral symmetry and soft body, in general of dimensions reduced with some notable exceptions as the giant squids. The body is clear basically of a head, often not differentiated, a visceral mass covered by the mantle (that it secretes also the shell when it exists), and a foot in position ventral.

The terrestrial snails are mollusks with the well developed foot and capable of breathing atmospheric air. It constitutes a very abundant group.