Bladder snails

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Bladder snails
Bladder snail

Bladder snail

Systematics
Trunk : Molluscs (mollusca)
Class : Snails (gastropoda)
Order : Lung snails (pulmonata)
Subordination : Water lung snails (Basommatophora)
Family : Bladder snails
Scientific name
Physidae
Fitzinger , 1833
The shell of this bladder snail is about 1 cm long. It is probably the species Physella acuta (slim habit! However, Physella heterostropha is very similar). However, some authors see both as belonging to one species.

The bladder snails (Physidae) are a family of the water snails (Basommatophora) within the order of the lung snails (Pulmonata). About 80 species are known worldwide.

features

The smooth, shiny shell of the bladder snails is left-wound and ends in a pointed apex. They have long and thin antennae that are pointed. The eyes are at the base of the antennae. The foot is relatively narrow and is pointed at the back. They can move in the water at remarkable speeds for snails . There is no secondary gill.

Similar forms : In African regions the representatives of the bladder snail can be confused externally with some species of the genus Bulinus (from the family of poppy snails ); in fact, quite a number of species were previously described as physa , which are now assigned to Bulinus .

Habitat and way of life

The bladder snails live in stagnant and slowly flowing water. Many species also tolerate less favorable water conditions such as eutrophic or acidic waters. They feed on rotting plant debris and detritus , but also algae ( diatoms , etc.). The eggs are laid in the form of soft elongated egg masses.

Distribution and number of species

The species of the bladder snail family are primarily distributed in the Holarctic . In America, however, they are also found in Central and South America. Through anthropogenic displacement, bladder snail species (especially Physella acuta ) have also been transported to many other regions of the world, such as Indonesia, New Zealand, Australia, India and South Africa.

In Central Europe there are currently three genera ( Physa , Physella and Aplexa ) with four species, including the species Physella heterostropha , which was introduced from North America . The exact number of genus and species cannot be given because, among other things, the species separation between Physa acuta and the introduced Physella heterostropha is not always clear.

paleontology

Fossil finds that could belong to the bladder snail family have been reported from the early Triassic (a good 200 million years ago), but the assignment of these ancient findings is not very reliable due to the limited traditional features. Modern genera can be found from the Miocene (especially Lower Pannonian approx. 10–11 million years ago) in what was then the Pannonian Sea of ​​the Vienna Basin (e.g. Aplexa cf. subhypnorum Gottschick 1920).

Systematics

External system : Often the bladder snails are grouped together with the plate snails in a superfamily ( Planorboidea ). Among other things, they share the characteristics of the poppy snails that they are anatomically left-wound and that they develop long and thin (thread-like) antennae. More recent molecular genetic findings also suggest that these two families are closely related.

Internal systematics : The following overview follows that of Bouchet & Rocroi (2005), who subdivides the family into two subfamilies, each with several tribi and thus also follows Taylor (2003). There are now more recent molecular genetic studies.

Individual evidence

  1. ↑ Henk K. Mienis: New world physids don't know borders: exotic Physidae in Indonesia. Ellipsaria, 7 (2): 8-9, Chattanooga 2005
  2. ↑ Neisha J. Cope and Michael Winterbourn: Competitive interactions between two successful molluscan invaders of freshwaters: to experimental study. Aquatic Ecology, 38 (1): 83-91, Dordrecht 2004 ISSN  1386-2588
  3. ↑ Ben J. Kefford, Alexander Dalton, Carolyn G. Palmer and Dayanthi Nugegoda: The salinity tolerance of eggs and hatchlings of selected aquatic macroinvertebrates in south-east Australia and South Africa. Hydrobiologia, 517: 179-192, Dordrecht 2004 ISSN  0018-8158
  4. ^ RK Sinha, H. Nesemann and G. Sharma: New records of Physa (Gastropoda: Physidae) from Indian subcontinent. Club Conchylia Information 34 (4-6): 3-11, Ludwigsburg 2003 ISSN  0931-797X
  5. ↑ CC Appleton: Alien and invasive fresh water Gastropoda in South Africa. African Journal of Aquatic Science, 28 (1): 69-81, Grahamstown 2003 ISSN  1608-5914
  6. ↑ Peter Glöer, Claus Meier-Brook: freshwater molluscs . 12th adult Ed., DJN , Hamburg ISBN 3-923376-02-2 (1998)
  7. ^ MJ Benton (Ed.): The Fossil Record 2. Chapman & Hall, London 1993.
  8. ↑ M. Harzhauser, H. Binder: Synopsis of the Late Miocene mollusc fauna of the classical sections Richardhof and Eichkogel in the Vienna Basin. Arch. Molluscology 133: 1-57 (2004)
  9. ↑ A. Klussmann-Kolb , A. Dinapoli, K. Kuhn, B. Streit, C. Albrecht: From sea to land and beyond - New insights into the evolution of euthyneuran Gastropoda (Mollusca). BMC Evolutionary Biology 2008, 8:57. doi : 10.1186 / 1471-2148-8-57 . (2008)
  10. ↑ Philippe Bouchet & Jean-Pierre Rocroi: Part 2. Working classification of the Gastropoda . Malacologia, 47: 239-283, Ann Arbor 2005 ISSN  0076-2997
  11. ^ Dwight W. Taylor: Introduction to Physidae (Gastropoda: Hygrophila); biogeography, classification, morphology. Revista de biología tropical, 51: 1-287, San José 2003 ISSN  0034-7744
  12. ↑ Amy R. Wethington, Charles Lydeard: A molecular phylogeny of Physidae (Gastropoda: Basommatophora) based on mitochondrial DNA sequences. Journal Molluscan Studies: doi : 10.1093 / mollus / eym021 (2007)

literature

  • 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 : Physidae  - Collection of images, videos and audio files