Pond snails

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Pond snails
Pointed pond snail (Viviparus contectus), shell

Pointed pond snail ( Viviparus contectus ), shell

Systematics
Class : Snails (gastropoda)
Subclass : Orthogastropoda
Superordinate : Caenogastropoda
Order : Architaenioglossa
Superfamily : Viviparoidea
Family : Pond snails
Scientific name
Viviparidae
Lamarck , 1809

Marsh snails (Viviparidae) are a (with the exception of South America and Antarctica) family of freshwater snails that are found in the order of the Architaenioglossa .

features

The housing is comparatively large at up to 5 cm; the marsh snails, together with the European mud snail, are among the largest freshwater snails in Central Europe. They have a fixed lid ( operculum ) that is attached to the foot. With this cover you can close the thick-walled housing tightly. This closure plays an important role in wintering.

Marsh snails are viviparous. Her scientific name Viviparus also relates to this . In Central Europe they are the only viviparous snails.

Reproduction

Viviparidae are separate sexes, not hermaphrodites like many other snail species. The male's right antennae are shorter and thicker than the left (the females are equally thick). This feeler contains the reproductive organ with which the sperm are brought into the female sexual opening. The eggs develop in an enlarged terminal part of the female ovary. There the embryos feed on a protein-containing liquid. There are usually several young animals in different stages of development in one mother. The oldest animal is then born individually ( ovoviviparous ). The juvenile snails are fully developed at birth, up to 10 mm in size (usually around 4 mm) and have bristles on their shell, which later fall off.

Lifestyle and diet

Marsh mud snails got their German name from the marsh mud snails of the genus Viviparus (see below), but in their entirety they are predominantly ground inhabitants of moving waters (lowland rivers, bank zones of lakes). Most of them crawl around on the ground as well as on stones and wood; less common in plants. In the aquarium, they rarely crawl up the pane, which can change if the panes are heavily overgrown with algae. Species from calmer waters burrow in the sand or mud for hours. Marsh snails have a wide range of food. They graze on algae and bacterial lawns, eat detritus and decaying plants and are also able to filter food particles and plankton from the water with the help of a slime web that is formed at the base of the gill . After a while the net tears, becomes clumped and transported out of the mantle cavity. Then the clumped slime web including the food particles is eaten. This acquisition of food through filtration is very unusual for freshwater snails.

The European species can also tolerate relatively high temperatures above 25 ° C.

Systematics

Numerous fossil species are known; several dozen species currently exist worldwide. Previously the family Viviparidae became the order mesogastropoda asked (MESOGASTROPODA). The middle snails belonged to the subclass fore gills (Prosobranchia). In the system presented here, there are three subfamilies with the following genera:

The delimitation of the individual genera within Asian Bellamyinae, which is rich in forms, is currently often controversial.

In Europe only the genus Viviparus lives with five species. The pond snails (Viviparidae) are scientifically named after this genus.

literature

  • Rosina Fechter, Gerhard Falkner: Steinbach's natural guide - molluscs - European marine and inland mollusks . Mosaik-Verlag, Munich 1990, ISBN 3570034143 .
  • Wolfgang Engelhardt: What lives in pools, brooks and ponds? kosmos nature guide . Franckh-Kosmos, Stuttgart 1989, ISBN 3440054446 .
  • Peter Glöer: The animal world of Germany. Mollusca I Freshwater gastropods of Northern and Central Europe Key to identification, way of life, distribution. 2. rework. Ed., 327 pages, ConchBooks, Hackenheim 2002 ISBN 3-925919-60-0 .

Web links

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