Limpet

For the underwater explosive device, see Limpet mine.

The word Limpet is a common name for a number of different kinds of saltwater and freshwater snails (aquatic gastropod mollusks). It is applied to those snails that have a simple shell which is basically conical in shape, and either is not coiled, or appears not to be coiled in the adult snails.

The name limpet is most often applied to members of the clade Patellogastropoda, the true limpets, which are all marine; however, the feature of a simple conical shell has arisen independently many times in gastropod evolution, in many different lineages, some of which have gills and some of which have a lung. The name is given on the basis of a limpet-like or "patelliform" shell, but the several groups of snails that have a shell of this form are not at all closely related to one another:

• Clade Patellogastropoda, example Patellidae
• Clade Vetigastropoda, examples Fissurellidae, Lepetelloidea
• Clade Neritimorpha, example Phenacolepadidae
• Clade Heterobranchia, group Opisthobranchia, example Tylodinidae
• Clade Heterobranchia, group Pulmonata, examples Siphonariidae, Latiidae, Trimusculidae

True limpets

The true limpet species Patella vulgata on a rock surface in Wales

Main article: Patellogastropoda

The phrase "true limpets" is used only for marine limpets in the ancient clade Patellogastropoda, which contains five living families and two fossil families.

Uses of the vernacular name

As well as being applied to the true limpets, the common name "limpet" is used for many other widely different snails, all of which have a shell that does not appear to be spirally coiled in the adult stage.

Marine limpets

The fossil fissurellid or "keyhole limpet", Diodora italica, from the Pliocene of Cyprus.

• The keyhole limpets and slit limpets - Fissurellidae
• The hydrothermal vent limpets – Neomphaloidea and Lepetodriloidea
• The nerite limpets – Phenacolepadidae
• The slipper limpets aka the slipper snails - Calyptraeidae
• The hoof limpets - Hipponix and other Hipponicidae

• The opisthobranch notaspidean limpets such as Tylodina and Umbraculum

• Two different groups of pulmonate false limpets
  • Basommatophora Siphonariidae
  • Stylommatophora Trimusculidae

Freshwater limpets

• The pulmonate river and lake limpets - Ancylidae

Most of the marine limpets have gills, whereas all the freshwater limpets and a few of the marine limpets have a mantle cavity that is adapted to breathe air and function as a lung (and in some cases has been again adapted to absorb oxygen from water) all these various kinds of snail are only very distantly related. In other words, the name limpet is used to describe various extremely diverse groups of gastropods that have independently evolved a shell of the same basic shape (see convergent evolution).

External links

• University of Hawaii Educational page from Christopher F. Bird, Dep't of Botany. Photos and detailed information distinguishing the different varieties.
• Lottia gigantea: taxonomy, facts, life cycle, bibliography
• Acmaeidae at the NCBI taxonomy website