Anisus vortex

Hot plate screw

The Hot Plate screw, also Spiral plate screw ( Anisus vortex ) is a water lung worm ( Basommatophora ) from the family of the plate screw ( Planorbidae ).

Features

The housing is only 0.8 to 1.1 mm high and measures to 9 mm in diameter. It has up to 7 whorls. The top is almost flat, slightly depressed the bottom. On top of the whorls are flat and separated by only a low tendency to weld. On the bottom of the whorls, however, are more curved and offset from each other by a distinct suture. At the last sitting high handling a keel is formed. The animals have a very short, rounded foot and quite a long thin antennas.

Reproduction

In the spring spawning several capsules, possibly trimmed with 2 to 12 and to 20 eggs. The development is highly dependent on temperature and lasts about 11 days at 18 °. Then slip the finished young animals.

Occurrence, lifestyle and dissemination

The Hot Plate snail lives in slow-moving or standing water on plants. It feeds on decaying leaves of aquatic plants and algae. They rasp pieces from the surface. It comes from Western Europe to Siberia. But is almost completely absent in Scandinavia; only in southern Sweden there are small deposits. It belongs to the water snails that in oxygen- rich waters " breathe underwater " ( the lungs are filled with water ), so do not come to the surface and are therefore not found often long (see Planorbis ).

Similar Species

The Dainty plate screw ( Anisus vorticulus ) is slightly smaller and has a more obtuse keel.

System

Endangering

The species is listed as endangered in Austria and Switzerland.