Barnacles

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Barnacles
Neritina natalensis (Reeve, 1845), a zebra lagoon

Neritina natalensis (Reeve, 1845), a zebra lagoon

Systematics
Class : Snails (gastropoda)
Subclass : Orthogastropoda
Superordinate : Neritimorpha
Order : Neritopsida
Superfamily : Neritoidea
Family : Barnacles
Scientific name
Neritidae
Rafinesque-Schmaltz , 1825

The barnacle snails (Neritidae), also called swimming snails , are a family of the order Neritopsida within the Neritimorpha , which in turn belongs to the subclass Orthogastropoda . The oldest evidence goes back to the Carboniferous .

features

The case is rolled up in a flat spiral and has only a few whorls. The mouth is flat. There is no spindle or, like the inner ducts, has been resorbed . The mouth can be closed by a calcareous operculum . The opercula has two processes inside, which are often typical of species or genera. Measured by their size, the barnacles have a very thick shell. They are thus adapted to a life in turbulent flowing water. The body is short and the housing almost completely covers the soft body when crawling. The head has a broad muzzle. The antennae are thin and pointed. Outside next to it sit the slightly stalked eyes. The animals are of separate sex. The male's penis sits under the right antennae.

Way of life and distribution

The species of the barnacles live mainly in the tidal area of the seas or in fast flowing rivers. Some species even colonize the land amphibiously. They prefer to sit on hard substrates and feed mainly on algae and sponges, which they scrape off the ground. Their powerful radula is even able to crack the hard shell of diatoms. The family is spread around the world. In Central and Northern Europe there is only one genus with four species. Other species occur in southern Europe, but some authors put them in a separate subgenus.

evolution

From a tribal point of view, the Neritidae belong to an original group ( Neritimorpha ), the oldest fossil records of which are regarded as reliable and date back to the Ordovician . Numerous peculiarities underline the basal status of the Neritidae within the higher gastropods . Its shell lacks the columella , the central axis. In addition, in many species the inner coils are resorbed in the course of further growth. This enables the characteristic capsule-shaped design of the housing. The pattern of their housing is so variable that one can often only identify species of the barnacles from different regions of their distribution area on the basis of their characteristic lid ( operculum ).

Systematics

The systematics of the entire family, including the freshwater species, has still not been studied satisfactorily. Current estimates range up to 175 species. This is due to the fact that in many cases the individual species cannot be reliably distinguished. A distinction is made between up to 30 genera and sub-genera. The families Septariidae Golikov & Starobogatov, 1975 and Protoneritidae Kittl, 1899 are younger synonyms. The most important genera and sub-genera:

literature

  • Klaus Bandel: The history of Theodoxus and Neritina connected with description and systematic evaluation of related Neritimorpha (Gastropoda). In: Messages from the Geological-Paleontological Institute of the University of Hamburg. 85: 65-164, Hamburg 2001 ISSN  0072-1115 .
  • Philippe Bouchet & Jean-Pierre Rocroi: Part 2. Working classification of the Gastropoda . In: Malacologia. 47: 239-283, Ann Arbor 2005 ISSN  0076-2997
  • Victor Millard: Classification of the Mollusca. A Classification of World Wide Mollusca . Rhine Road, South Africa 1997 ISBN 0-620-21261-6

Individual evidence

  1. ^ Václav Pfleger: Mollusks. 192 pp., Artia Publishing House, Prague 1984.

Web links

Commons : Neritidae  - Collection of images, videos and audio files