Viviparus contectus

Top mud snail ( Viviparus contectus ) Housing with operculum

The top mud snail ( Viviparus contectus ) is a freshwater snail from the family of river snails ( order Architaenioglossa ).

Features

The case measures up to 45 mm in height and 35 mm width. It has 6 to 6.5 turns and is greenish brown to black. The windings are offset stage and the navel is open. The apex is pointed. There are usually three red ribbons available on the turns. It forms under different conditions of life form various variants of ( cf V. virescens, V. and V. cf cf nigerrimus menzeli ).

Reproduction

The animals are like all members of the family Viviparidae viviparous ( ovoviviparous ). In the uterus of the female mature from 12-30 egg capsules during the summer approach gradually the boy, then usually leave the mantle cavity of the mother in a size of 2.5 to 10 mm.

Lifestyle and dissemination

V. contectus are found mainly in stagnant water, often in murky, weedy and veralgten muddy ponds and brooks ( cf. the German surname mud snail ). It also occurs in acidic bog ponds and swamps. This differs from most other contectus V. Viviparidae. She is a grazer, filter feeders or feed on detritus. The animals hibernate in the mud dug and can be up to 13 years old.

The species occurs in almost all of Europe. You lack in Norway, Finland and southern Europe.

Similar Species

You can see the two types is best distinguished by the dismissal of the individual whorls of the case: Viviparus viviparus has leaner, not stage remote housing turns; with V. contectus the bauchigeren whorls are clearly stage discontinued. This makes them a sharper impression. The umbilicus is at V. viviparus much narrower, almost closed.

Endangering

The top mud snail is out on the Red Lists of Germany and Austria as endangered, in Switzerland as endangered. She was admitted to the early warning of the Czech Republic. As sources of risk Machinery Entkrautungsmaßnahmen, other engineering measures and drainage of waters shall apply.