Clausilium

A clausilium is a housing closure, as it occurs in the family of door snails ( Clausiliidae ).

Morphology and function

The clausilium consists of a tongue- depending on the genus, spoon or spatula connected with an elastic band limestone slab, the side slides into the housing when the worm crawls out of its housing. If the mouth of the case has been sealed with the broad and shallow end of Clausiliums, the snail is inside some protection from predators.

The narrow end of the Clausiliums is located in a spiral around the columella sinuous fold in the shell interior. Due to the length of this pit and the muscle with which the screw moves the clausilium, it is able to fully retract the clausilium in the bowl.

In contrast to the operculum clausilium the door snails belonging to the shell and is connected to this firm, however, not attached to the soft body of the animal, so that also found in empty shells Clausilia. Nor is the clausilium equated with the temporarily formed in the winter cover ( Epiphragma ) of the snails.