Semi-slug
Encyclopedia
Semi-slugs, also spelled semislugs, are land gastropods whose shells
are too small for them to retract into, but the shell is not quite vestigial. The shell of some semi-slugs may not be easily visible on casual inspection, because the shell may be covered over with the mantle
.
This is a type of gastropod that is intermediate between a slug
(without an external shell) and a land snail
(with a large enough shell to retract completely into).
There exist a number of gastropod families that have semi-slugs species. There exist about 1000 species of semi-slugs in comparison to about only 500 species of slugs.
Gastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...
are too small for them to retract into, but the shell is not quite vestigial. The shell of some semi-slugs may not be easily visible on casual inspection, because the shell may be covered over with the mantle
Mantle (mollusc)
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...
.
This is a type of gastropod that is intermediate between a slug
Slug
Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...
(without an external shell) and a land snail
Land snail
A land snail is any of the many species of snail that live on land, as opposed to those that live in salt water and fresh water. Land snails are terrestrial gastropod mollusks that have shells, It is not always an easy matter to say which species are terrestrial, because some are more or less...
(with a large enough shell to retract completely into).
There exist a number of gastropod families that have semi-slugs species. There exist about 1000 species of semi-slugs in comparison to about only 500 species of slugs.
Examples
Semi-slugs from the Neotropics:- family Amphibulimidae: AmphibulimaAmphibulimaAmphibulima is a genus of air-breathing land snails, a terrestrial pulmonate gastropod mollusks in the family Orthalicidae.Amphibulima is the type genus of the subfamily Amphibuliminae.- Species :Species in the genus Amphibulima include:...
and Gaeotis - family XanthonychidaeXanthonychidaeXanthonychidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Helicoidea.This family is within the clade Eupulmonata ....
: Cryptostrakon, Semiconchula and Xanthonyx - family PleurodontidaePleurodontidaePleurodontidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Helicoidea.This family is classified within the clade Stylommatophora within the clade Eupulmonata...
: Coloniconcha prima - Semi-slugs do exist but are exceptional in the CamaenidaeCamaenidaeCamaenidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Helicoidea.This is one of the most diverse families in the clade Stylommatophora....
.