Physidae

Bladder snail

The bladder worm ( Physidae ) are a family of water snails ( Basommatophora ) within the order of snails ( Pulmonata ). Worldwide there are about 80 known species.

Features

The shiny - smooth case is linksgewunden in the bladder snails and ends in a pointed apex. They have long, thin probes that are tapered. The eyes are located at the base of the sensor. The foot is relatively narrow and pointed behind. You can move with remarkable speed for snails in the water. A secondary gill does not exist.

Similar forms: In African regions, representatives of the bladder snails can externally with some species of the genus Bulinus be confused ( from the family of plate screw ); actually a number of species have been described as Physa, which are now placed on Bulinus formerly.

Habitat and behavior

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

Distribution and number of species

The species of the family of the bladder snails are primarily distributed Holarctic. In America they come but also in Central and South America. Anthropogenic procrastination bladder worm species have been (especially Physella acuta) also spread to many other regions of the world, so to Indonesia, New Zealand, Australia, India and South Africa.

In Central Europe, currently three genera ( Physa, Physella and Aplexa ) live with four species, including, introduced from North America kind Physella heterostropha. The exact genus and species number can not be specified because, among other things Arttrennung Physa acuta and between the entrained Physella heterostropha is not always clear ..

Paleontology

Fossils that might belong to the family of bladder snails are indeed already reported from the Early Triassic Period ( 200 million years ), but the assignment of these old results due to the limited traditional features are not very safe. Modern genera are secured from the Miocene (especially Lower Pannonian front of about 10-11 million years ago) in what was then Pannon Lake of the Vienna Basin to find (eg Aplexa cf subhypnorum Gottschick 1920).

System

External system: In many cases the bladder snails are combined with the plate screw in a superfamily ( Planorboidea ). With the plate screw they share, among other things, the properties that they are linksgewunden anatomically and that they form long and thin ( thread-like ) probe. More recent molecular genetic findings suggest that the close relationship of these two families.

Internal system: The following table follows that of Bouchet & Rocroi (2005), who divided the family into two subfamilies, each with several Tribi and thus also Taylor ( 2003) follows. There are now newer molecular genetic studies.

  • Subfamily Physinae Fitzinger, 1833 Tribus Physini Fitzinger, 1833 Beringophysa Starobogatov & Budnikova, 1976
  • Laurentiphysa Taylor, 2003
  • Physa Draparnaud, 1801 Physa fontinalis - Source bladder snail
  • Haitia Clench & Aguayo, 1932
  • Archiphysa Taylor, 2003
  • Chiapaphysa Taylor, 2003
  • Petrophysa Pilsbry, 1926
  • Physella Haldeman 1842 Physella acuta - Peak bladder worm ( Draparnaud, 1805)
  • Tribus Aplexini Starobogatov, 1967 Amuraplexa Starobotatov, Prozorova & Zatravkin, 1989
  • Aplexa Fleming, 1820 Aplexa hypnorum - moss bladder snail
  • Amecanauta Taylor, 2003
  • Mayabina Tayor, 2003
  • Mexinauta Taylor, 2003
  • Tropinauta Taylor, 2003
  • Austrinauta Taylor, 2003
  • Caribnauta Taylor, 2003
  • Afrophysa Starobogatov, 1967
  • Stenophysa Martens, 1898
Leopold Fitzinger
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