The word “gastropod” means "belly-footed". The gastropods make up the largest class of molluscs and may be marine, freshwater or terrestrial. Most have gills, a well-developed head with eyes and tentacles, and a single shell. This shell may be coiled or cone shaped. Some gastropods can seal off the aperture (opening) of their coiled shells with a "trapdoor" called an operculum. Some gastropods may be hermaphrodites, having both male and female reproductive organs.
Gastropods include snails, slugs, conches, periwinkles, whelks, and cone shells. Most Most gastropods are herbivoures, although some like the cone shell and the Australian predatory sea snail are predatory.