Gastropoda (Cuvier, 1797) Print

Gastropods are a class of living mollusks that has maintained a way of life and a structure relatively similar to the common ancestor of the phylum. Include snails (Helix & Limax) and numerous marine animals that are known more for their shells (although a large number of them, including most of the Heterobranchia and all the sea slugs, haven't a shel) .

Description

The most striking change compared to the ancestral mollusc is a lot of guts rotation around an axis vertical and its winding spiral, involving also the shell. Gastropods have therefore lost bilateral symmetry. The foot and head are evident and there are antennas on the head with tactile and / or visual features. Marine gastropods, mostly are benthic, may also have a mass of several kilograms. Terrestrial have evolved a lung in the cavity of the mantle, are in any case confined to damp environments. Both aquatic species, both terrestrial lost their shell.