Clam shell
The mussel shells (Conchostraca) belong to the branch shrimp (Anostraca) and the back shell (Notostraca) to the Branchiopods or "Tadpole Shrimp" and are therefore to be counted among the living fossils . They have been preserved in almost unchanged form since the Silurian .
The mussel shells are classified within the Branchiopods in the order of the claw tails , but the position of this group ( taxon ) within the systematics of the leaf crabs or their validity as an independent taxon is still under scientific discussion. In recent times there has been a tendency for the majority to believe that the mussel shells do not form a natural unit.
They owe their name to their two-part or two-lobed shell, which protects them from injury and externally resembles a clam. They become between 0.5 and 2 cm long and filter their food, which usually consists of suspended particles or algae, from the water. Their habitat is often short-term ( astatic ) waters. Their development from egg to adult animal takes place within a few days, whereby the hard-shelled eggs are able to withstand prolonged drying out of the water, heat or frost.
Mussel shells are rare and not to be confused with the common mussel crabs or with the brachiopods .
literature
- Erna Aetsch (Ed.): Tadpole Shrimp Austria: living fossils in short-lived waters . Upper Austria. Landesmuseum, Linz 1996, ISBN 3-900746-95-8 .
- Henri J. Dumont, Stefan V. Negrea: Branchiopoda . Backhuys Publ., Leyden 2002, ISBN 90-5782-112-5 . (Determination book)