Ark clam

Noah's Ark ( Arca NoAE )

The ark shells ( Arcidae ) are a family shellfish from the order of Arcoida. Currently, about 200 species are provided to the family of ark shells.

Features

The housing of the ark shells are small to medium in size (about 1.5 cm to about 10 cm). The shape varies from rounded - rectangular, oblong- elliptic to about almost roundish. The surface is often ornamented with strong radial ribs, but may be covered with fine concentric and radial lines stripes. The shell thickness is very different from all the species of thin-skinned to thick- pronounced. The castle is taxodont ( reihenzähnig ), that is, it is straight and consists of many, nearly equal teeth. There are two sphincters present, which are approximately the same size ( isomyar ). The foot is, in contrast to almost all other mussel species, flattened on the bottom, and thus resembles more of a creeping as a Grabfuß. A special feature of the ark shells is the transport of oxygen in the tissues and blood using the blood pigment hemoglobin, which occurs otherwise with few exceptions only in vertebrates. Other molluscs have the blood pigment hemocyanin, or do not have blood dyes for oxygen transport. The acquisition of the blood pigment hemoglobin is attributed to the lifestyle of the ark shells in oxygen-poor water. Some species of shallow water have simple eyes on the mantle margin.

Occurrence and distribution of life

The species of the family ark shells live mainly in the tropics and subtropics, a few species penetrate into the temperate latitudes. Four species occur in the North Sea and the Mediterranean. They usually live with a byssus attached to hard substrate. They come up in the tidal area before about 4000 m depth. Noah's Ark shell until about 15 years old.

Economic Importance

Many, especially the larger species are caught commercially and sold as seafood ( "Seafood "). The mussels are dredged " gedredgt " or collected by divers.

System

The family, some authors still divided into the following subfamilies: . Arcinae Lamarck, 1809 Anadarinae Reinhard, 1935, Noetiinae Stewart, 1930, Striarcinae McNeil, 1938 and Trinacriinae McNeil, 1937 However, other authors do not use this subfamily structure. The Noetiidae be z.T. construed as independent family.

• Acar Gray, 1857
• Anadara Gray, 1847
• Arca Linnaeus, 1758 Noah's Ark ( Arca NoAE )