Class of the phylum Mollusca. Snails. The shell is an asymmetrical spiral, the axis of which is the columella; the shell may be lost secondarily. When crawling on the extended foot and feeding, the gastropod carries the shell; when disturbed, the body is completely withdrawn into the shell, which is closed with the operculum. Gastropods live on land, in freshwater, and in the sea. They are divided according to the type of gills into the subclasses Prosobranchia (2 gills), Ophistobranchia (1 gill) and Pulmonata (gill absent, lung developed), with marine snails among all types.

Alternative form for gasteropods : gastropods.