Gastropods Gastropods Gastropoda is a class in the Phylum Mollusca. Most gastropods are marine, although some are pulmonates. Some common gastropods are slugs and snails. The body of Gastropods is divided into a head, foot, and visceral mass.
Gastropods have a shell, although some have lost their shells through evolution.
Gastropods are subdivided by shell form, or the absence of a shell, internal anatomy, size and shape of tentacles, foot, and mantle, as well as type of breathing organ. Gastropods have an embryonic process known as torsion, which distinguishes them from other mollusks. One side of the visceral mass grows faster than the other, which causes the body to form the shape of a snailshell. Torsion is evident in the helmetshell. Slugs are snails that have evolved and lost their shells in order to be able to fit into smaller spaces.