Conch shell
The mussel shell is the outer skeleton ( exoskeleton ) of the mussels . It is a special form of the mollusc shell that all shell molluscs have.
The mussel housing consists of two shell-shaped flaps that surround the soft body of the mussels. The two valves are held together by two internal sphincters and are articulated on the back by a strap, the so-called ligament . The attachment point of the sphincter muscle can often be seen on the inside of the mussel shells. The buckle strap is very elastic and keeps the shell halves tensioned. It works antagonistically to the sphincter muscles: The tension of the lock strap opens the shell. After the animal dies, the sphincter muscles relax (or become detached from the shell) - as a result, the mussel opens.
anatomy
The gaping shells are damaged by mechanical stress, such as. B. the surf, easily separated. You will therefore find individual shell halves much more often than a “doublet”, which still consists of both flaps.
So that the two halves of the clamshell do not slip sideways, many types have so-called lock teeth , which wedge the two halves into one another when closed. The lock teeth consist of interlocking, tooth-shaped or strip-shaped elevations on the inner back edge of the flaps and corresponding pits on the counter flap. Most mussels are heterodontic , which means that their lock consists of a few main teeth and up to four bar-shaped posterior teeth. Because of the variety of different configurations of the lock teeth, they can often be used for the zoological and systematic classification of the mussel.
Interlocking notches on the lower edge of the shell can prevent it from slipping sideways. These notches are also defining characteristics of a mussel species. The curved shape gives clam shells their overall stability.
composition
Mussel shells consist mainly of calcium carbonate (lime), which occurs in the form of the mineral aragonite . The aragonite crystals are cemented by an organic substance, the conchyn . The mussel shells are formed by the mantle , a skin fold of the mussel. The attachment point of the mantle can also be seen on the inside of many mussel shells (mantle edge). The bowls consist of three layers: the colored periostracum , the prism layer and the often rainbow-colored shimmering mother-of-pearl layer (hypostracum).
use
Mussel shells are widely used, for example as jewelry material (mother-of-pearl) or when feeding birds or reptiles as a source of calcium, including for tortoises. Fossil mussel shells form part of the natural stone shell limestone, which is partially used as a building material . Already in the Indus culture around 2800–1800 BC. The processing of mollusc shells can be proven. All over the world, the shells of various types of mussels were and are still processed into small, perforated discs, strung on strings and traded as mussel money . The taboo shell money of the Tolai people on the island of New Britain in Papua New Guinea has deep ritual , religious and spiritual meanings in addition to its importance as an official complementary currency .
The Shell oil company uses an upside-down stylized scallop as its company logo . In heraldry , the shells of the scallop are depicted as heraldic animals , for example in the coats of arms of the cities of Ennigerloh , Mainz-Kastel or Bad Mingolsheim (see also the list of coats of arms with the scallop and shell as heraldic animal ).
Shell company logo
Ennigerloh coat of arms
Coat of arms of Mainz-Kastel
Bad Mingolsheim coat of arms
Individual evidence
- ↑ Gert Lindner: Collecting and determining mussels and snails: The most common and most beautiful species. For the beaches of Europe. 3rd, revised edition, new edition. BLV Buchverlag, Munich 2008, ISBN 978-3835403741 , p. 14.