Neritidae

Neritina natalensis ( Reeve, 1845), a zebra Rennschnecke

The Kahn snails ( Neritidae ), also called swimming snails, are a family of the order Neritopsida within the Neritimorpha, which is in turn supplied it to subclass Orthogastropoda. The earliest evidence dates back to the Carboniferous.

Features

The casing is rolled flat spiral and has few whorls. The muzzle is flat. A spindle is not available or has been absorbed as the inner whorls. The mouth may be closed by a calcareous operculum. The opercula have inside two extensions, which are often characteristic of species or genera. Judging by its size, the Kahn snails have a very thick skin. They are thus adapted to living in turbulent flowing water. The body is short, and the case covers the soft body while crawling almost completely. The head has a broad muzzle. The sensors are thin and pointed. Outdoor sit by the slightly stalked eyes. The animals are dioecious. The penis of the male sits under the right sensor.

Lifestyle and dissemination

The types of Kahn snails live mainly in the tidal area of the oceans or in fast flowing rivers. Some species colonize amphibian even the country. They sit preferably on hard substrates and feed mainly on algae and sponges that they rasp from the ground. Her powerful radula is even capable of the hard shell of diatoms to crack. The family is distributed worldwide. In Central and Northern Europe, only one genus with four species occurs. In southern Europe, more species occur, but these are found by many authors in a separate subgenus.

Evolution

Seen tribal History includes the Neritidae to an original group ( Neritimorpha ) ranging in oldest than secured prestigious Fossil evidence dating back to the Ordovician. Numerous features underline the basal status of Neritidae within the higher gastropods. Your shell lacks columella, the central axis. In addition, the internal windings are absorbed in the course of further growth in many species. This allows the characteristic capsule-shaped design of the housing. The pattern of their housing is so variable that one can determine the types Kahn snails from different regions of their range often only to its characteristic lid (operculum ).

System

The systematics of the entire family, including the freshwater -dwelling species is still not investigated satisfactorily. Current estimates range up to 175 species. This is because in many cases, the individual species can not be securely held apart. It can be distinguished up to 30 genera and subgenera. The families Septariidae Golikov & Starobogatov, 1975 Protoneritidae Kittl, 1899 are junior synonyms. The most important genera and subgenera:

• Subfamily Rafinesque - Schmaltz Neritinae, 1815 Tribus Rafinesque - Schmaltz Neritini, 1815 Genus Bathynerita Clarke, 1989
• Genus † Calyptronerita Le Renard, 1980
• Genus Nerita Linnaeus, 1758 Subgenus Adenerita Dekker, 2000
• Subgenus Amphinerita von Martens, 1887
• Subgenus Cymostyla von Martens, 1887
• Subgenus Heminerita von Martens, 1887
• Subgenus Ilynerita von Martens, 1887
• Subgenus Linne Rita Vermeij, 1984
• Subgenus Melanerita von Martens, 1887
• Subgenus face Rita Dekker, 2000
• Subgenus Nerita Linnaeus, 1758
• Subgenus Ritena Gray, 1858
• Subgenus Theliostyla Mörch, 1852

• Tribus Neritinini Poey, 1852 Rafinesque - Schmaltz genus Neritina, 1815 Subgenus Dostia Gray, 1847
• Subgenus Rafinesque - Schmaltz Neritina, 1815 Neritina turrita (Zebra Rennschnecke )
• Neritina natalensis Reeve, 1845
• Neritina pulli screened L., 1767

• Vittina coromandeliana Sowerby, 1836

• Genus Clithon Montfort, 1810
• Genus Clypeolum Récluz, 1842
• Genus Fluvinerita Pilsbry, 1932
• Genus Neripteron Lesson, 1831
• Genus Neritodryas von Martens, 1869
• Genus Puperita Gray, 1857 Puperita pupa

• Subgenus Theodoxus Montfort, 1810 Theodoxus fluviatilis ( Common nerite )
• Theodoxus danubialis ( Danube nerite )

• Genus Gaillardotia Bourguignat 1877
• Melvill & Standen genus Magadis, 1899
• Genus Pisulina Nevill & Nevill, 1869
• Genus Emerald Ella Baker, 1923
• Genus Smaragdia Issel, 1869
• Genus Emerald Ista Iredale, 1936

• Genus Velates Montfort, 1810