Terrestrial Mollusk (Land Snails and Slugs)

Terrestrial or land mollusks are an ecological group that includes all mollusks that live on land in contrast to freshwater and marine mollusks.

This group includes land snails and land slugs. The term land slug or snail is rather taxonomically ambiguous since these terms refer to taxa with either having no shell, a very reduced shell, a small internal shell, to large shells, big enough for the organism to retract into full. Some families contain members fitting into a range of shell “types”.

Loss of the shell has taken place many times in different groups that are not evolutionarily closely related, and land snails and slugs are most often treated together as a single group in specialized malacological literature.

All terrestrial mollusks belong to the class Gastropoda. Since colonization of the land took place several times during the evolutionary past, and as a result terrestrial mollusks are classified in several different, often not closely related, gastropod taxa.

There are about 35 thousand species of terrestrial mollusks, most of which belong to the order (in some sources suborder or infraorder) Stylommatophora.

Terrestrial mollusks occur across most of the planet, except for Antarctica and some islands. They inhabit a wide range of ecosystems, from deserts and tundras to rainforests.

In terms of survival, this group of species is currently one of the most threatened with more known species extinctions of terrestrial mollusks than in any other group of organisms.

Land mollusks have a muscular foot and use mucus to enable them to crawl over rough surfaces and to keep their soft bodies from drying out. In terms of reproduction, many are dioecious (either male or female), but pulmonate mollusks are hermaphrodites (have a full set of male and female sex organs) and most lay clutches of eggs in the soil.

A wide range of different vertebrate and invertebrate animals prey on land mollusks. They are used as food by humans in various cultures worldwide and are raised on farms in some areas for use as food.