Myoida

Sand gaper ( Mya arenaria )

The Myoida are an order of mussels ( Bivalvia ), which is expected to superorder within the subclass Heterodonta Autolamellibranchiata. The first, somewhat in question representatives of this group are known from the Carboniferous, the first secure representatives from the Permian.

Characteristics

The housing of the Myoida can equal or inequivalve, gape most housing. The shell is usually thin and aragonitisch with kreuzlamellaren microstructures without nacre layers. The castle is largely reduced in most forms. The ligament is located externally or internally on a Chondrophor. There are approximately equal before large sphincter or sphincter of unequal size.

Way of life

The Myoida flat to live buried deep in soft sediment or on the sediment. Accordingly, there are forms with very large siphons. The superfamily Pholadoidea drilled in wood ( " shipworm ").

System

For reasons of priority, the order would have actually considered Pholadoida Chenu, are referred to in 1862, because this name is older than the order name Myoida Stoliczka, 1870. However, the strict International rules for Zoological Nomenclature only on type, genus, and family level apply. The order is divided into two by some malacologists subordination Myina and Pholadina. Others divide the order in only two superfamilies:

• Superfamily Myoidea Lamarck, 1809 (eg sand gaper ( Mya arenaria ), truncate Klaffmuschel ( Mya truncata ) )
• Superfamily Pholadoidea Lamarck, 1809 (eg shipworms ( Teredinidae ) shipworm ( Teredo navalis ), White piddock ( Barnea candida ), Krause piddock ( Zirfaea crispata ) )

In the previous classifications are the

• Gastrochaenoidea and the
• Hiatelloidea (eg elephant trunk clam ( Panopea abrupta ) )

Also still made ​​to order Myoida. Bieler & Mikkelsen (2006), they have transferred in the order Veneroida.