The best-known gastropods are land slugs and snails, but more than half of all species live in a marine environment.

The various families of land slugs are not very closely related, despite a superficial similarity in the overall body form.

Thus, for example, the various families of land slugs are not very closely related to one another, despite a superficial similarity in the overall body form.

In a land slug, when the pneumostome is wide open, it is usually very clearly visible on the right side of the animal.

This is a land slug which breathes air, a pulmonate.

Despite superficial similarities, not all land slugs are in the same family or superfamily.

When attacked, most land slugs will simply retract the head and contract the body, but stay firmly attached to the substrate.

Trigonochlamys imitatrix is a species of predatory air-breathing land slug.

Parmacellilla filipowitschi is a species of predatory air-breathing land slug.

In the land slugs, the shell is reduced or absent, and the body is streamlined.