Terrestrial molluscs or land molluscs (mollusks) are an

ecological Ecology () is the natural science of the relationships among living organisms and their environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere levels. Ecology overlaps with the closely re ...

group that includes all

molluscs Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

that live on

land Land, also known as dry land, ground, or earth, is the solid terrestrial surface of Earth not submerged by the ocean or another body of water. It makes up 29.2% of Earth's surface and includes all continents and islands. Earth's land sur ...

in contrast to

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

and marine molluscs. They probably first occurred in the

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

, arising from freshwater ones.

Characteristics

This group includes

land snail A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial molluscs, terrestrial gastropod mollusks that have gastropod shell, shel ...

s and land 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 specialized malacological literature.Barker G. M. (ed.)
The biology of terrestrial molluscs
'. CABI Publishing, 2001, 558 pp. .Barker G. M. (ed.)
Natural enemies of terrestrial molluscs
'. CABI Publishing, 2004, 644 pp. . All terrestrial molluscs belong to the class

Gastropoda Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

. However, colonization of the land took place several times during the

evolutionary Evolution is the change in the heritable characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certa ...

past, and as a result terrestrial molluscs are classified in several different, often not closely related, gastropod

taxa In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

. 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 of

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

and some islands. They inhabit a wide range of ecosystems, from

desert A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...

s and

tundra In physical geography, a tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. There are three regions and associated types of tundra: #Arctic, Arctic, Alpine tundra, Alpine, and #Antarctic ...

s to

rainforest Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...

s. In terms of survival, this group of species is currently one of the most threatened; there are more known species extinctions of terrestrial molluscs than in any other group of organisms.Cameron R. ''Slugs and snails''. HarperCollins Publishers, London, 2016, 508 pp. .

Taxonomic diversity

According to an estimate from Cameron, of the 409 existing gastropod

families Family (from ) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictability, structure, and safety as ...

, 119 include terrestrial molluscs. Among these 119 families, 104 are Stylommatophora, 7 are terrestrial pulmonates other than stylommatophorans, and 8 are operculates (formerly " prosobranchs", molluscs with an operculum, a group that primarily consists of marine snails). "Prosobranchs" *

Cyclophoroidea Cyclophoroidea is a superfamily of land snails with an operculum, terrestrial gastropods within the order Architaenioglossa, that belongs to the subclass Caenogastropoda.Bouchet, P.; Rosenberg, G.; Gofas, S. (2015). Cyclophoroidea Gray, 1847. ...

(up to 10 families in different classifications) * Helicinidae,

Proserpinellidae Proserpinellidae is a taxonomic family of land snails with an operculum, terrestrial gastropod mollusks in the superfamily Helicinoidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). This family has no subfamilies ...

and

Proserpinidae Proserpinidae is a Taxonomy (biology), taxonomic family (biology), family of small land snails with an operculum (gastropod), operculum, gastropod mollusks in the superfamily Helicinoidea (according to the Taxonomy of the Gastropoda (Bouchet & Ro ...

(in the superfamily

Helicinoidea Helicinoidea is a taxonomic superfamily of land snails that have an operculum. In other words, they are terrestrial operculate gastropod mollusks. They are in the order Cycloneritida and are quite closely related to the marine and freshwater ...

) *

Pomatiidae The family Pomatiidae is a taxonomic family of small operculate land snails, terrestrial gastropod mollusks that can be found over the warmer parts of the Old World. In the older literature, this family is designated as Pomatiasidae. This fam ...

(in the superfamily

Littorinoidea Littorinoidea are a Taxonomic rank, superfamily of both sea snails and land snails which have a gill and an operculum (gastropod), operculum, Terrestrial animal, terrestrial and marine (ocean), marine gastropod Mollusc, mollusks in the clade Litt ...

, which consist mainly of marine snails) * Assimineidae and Truncatellidae (in the superfamily

Truncatelloidea Truncatelloidea is a family (biology), superfamily of snails, gastropod mollusc, mollusks in the clade Caenogastropoda.Bouchet, P. (2013). ''Truncatelloidea''. Retrieved through: World Register of Marine Species at http://www.marinespecies.org/a ...

, which consist mainly of aquatic snails; most species semi-marine) "Pulmonates" * Amphiboloidea (three families of land and semi-marine snails) *

Ellobioidea Ellobiidae, common name the hollow-shelled snails, is a family (biology), family of small air-breathing Land snail, land, Sea snail, marine, and brackish snails; pulmonate gastropod mollusks in the clade Eupulmonata.Bouchet, P. (2012). Ellobiida ...

( Ellobiida) (1–5 families in different classifications, some of the species live in litoral both in marine and terrestrial habitats) *

Systellommatophora The Systellommatophora (synonym Gymnomorpha) is a clade of primitive, air-breathing slugs, according to the taxonomy of the Gastropoda (Bouchet & Rocroi, 2005). They are marine and terrestrial pulmonate gastropods within the Heterobranchia. T ...

(3 families of land and semi-marine slugs) * Stylommatophora (more than 100 families of land snails and slugs)

Best known terrestrial malacologists

Oskar Boettger Oskar Boettger (; 31 March 1844 – 25 September 1910) was a German zoologist who was a native of Frankfurt am Main. He was an uncle of the noted malacologist Caesar Rudolf Boettger (1888–1976). From 1863 to 1866 he studied at the Bergakademie ...

* Jacques Philippe Raymond Draparnaud *

Wilhelm Kobelt Wilhelm Kobelt (20 February 1840 – 26 March 1916) was a German zoologist born in Alsfeld, Grand Duchy of Hesse. He specialized in the field of malacology. Kobelt was born in Alsfeld to parish priest Wilhelm (1809–74) and Auguste (1815–97) ...

Henry Augustus Pilsbry Henry Augustus Pilsbry (7 December 1862 – 26 October 1957) was an American biologist, malacologist and carcinologist, among other areas of study. He was a dominant presence in many fields of invertebrate taxonomy for the better part of a cent ...

* Emil Adolf Rossmässler *

Heinrich Simroth Heinrich Rudolf Simroth (10 May 1851 Riestedt (now a part of Sangerhausen) – 31 August 1917 Gautzsch near Leipzig), was a German zoologist and malacologist. He was a professor of zoology in Leipzig. Academic career: 1888–1917 University of Le ...

Carl Agardh Westerlund Carl Agardh Westerlund (12 January 1831 – 28 February 1908 in Ronneby) was a Swedish malacologist. Biography Westerlund was born at Berga in Kalmar County, Sweden. He became a student in Uppsala University in 1853 and studied at Lund U ...

References

Sources

Most important literature