Gastropods, the only mollusks with terrestrial representatives, occur in nearly every habitat type. On land they’re found in wet and dry areas, including deserts; from low to high elevations; from tropical to polar latitudes (as high as there is humic material and leaf litter). Inland aquatic habitats range from puddles to lakes and rivers, fresh to salt water, and include sulfurous hot springs. In the ocean they occupy all habitat types, from deep ocean basins and hydrothermal vent communities to high intertidal splash zones and from warm tropical waters to cold polar seas.
Gastropods are distributed throughout the ocean, and on land, essentially everywhere except the most extreme polar regions. They occur as far north as Point Barrow, Alaska (USA) at 71°23′20″N (J. Nekola, personal communication, January 17, 2011) and as far south as the sub-Antarctic islands (Solem & van Bruggen, 1984). They do not occur on the Antarctic continent.