Terrestrial molluscs orland molluscs (mollusks) are anecological group that includes allmolluscs that live onland in contrast tofreshwater andmarine molluscs. They probably first occurred in theCarboniferous, arising fromfreshwater ones.[1]
This group includesland snails andland slugs. 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 specializedmalacological literature.[2][3]
All terrestrial molluscs belong to the classGastropoda. However, colonization of the land took place several times during theevolutionary past, and as a result terrestrial molluscs are classified in several different, often not closely related, gastropodtaxa.[2]
Terrestrial mollusks comprise about 35 thousand species, most of which belong to the order (in some sources suborder or infraorder)Stylommatophora.
Terrestrial molluscs occur across most of the planet, with the exception ofAntarctica and some islands. They inhabit a wide range of ecosystems, fromdeserts andtundras torainforests.
In terms of survival, this group of species is currently one of the most threatened; there are more known speciesextinctions of terrestrial molluscs than in any other group of organisms.[4]
According to an estimate from Cameron,[4] of the 409 existing gastropodfamilies, 119 include terrestrial molluscs. Among these 119 families, 104 areStylommatophora, 7 are terrestrialpulmonates other than stylommatophorans, and 8 are operculates (formerly "prosobranchs", molluscs with anoperculum, a group that primarily consists ofmarine snails).
"Prosobranchs"
"Pulmonates"
This article incorporates text from a publication now in thepublic domain: Howe, John Allen (1911). "Carboniferous System". InChisholm, Hugh (ed.).Encyclopædia Britannica. Vol. 5 (11th ed.). Cambridge University Press. pp. 309–313.