Flat-ribbed cockle
| Flat-ribbed cockle | ||||||||||||
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Flat-ribbed cockle ( Laevicardium crassum ) |
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| Laevicardium crassum | ||||||||||||
| ( Gmelin , 1791) |
The flat- ribbed cockle ( Laevicardium crassum ) is a type of mussel from the cockle family (Cardiidae), which belongs to the order of the Cardiida .
features
The flat-ribbed cockle, which has the same valve, but unequal-sided, slightly inflated housing, grows to a height of 75 mm and is only slightly shorter. It measures up to 45 mm in thickness. The shapes from the Mediterranean are generally somewhat smaller than the Atlantic shapes. The case is triangular to egg-shaped, but the shape is somewhat variable. The rear edge is longer and less curved than the front edge. The ventral margin is only slightly curved (crassum shape) or more strongly curved (gibba shape). The vortex is well in front of the middle of the length of the case.
The lock consists of two cardinal teeth in the right flap, the front one of which is significantly smaller. The upper of the two anterior lateral teeth is even smaller; there is another posterior lateral tooth. There are also two cardinal teeth in the left valve, the rear one of which is much smaller. In addition, there is (usually) an anterior and a posterior lateral tooth. Small secondary teeth can be formed under the anterior lateral tooth, the posterior lateral tooth can be reduced or absent. The jacket line is complete, without a jacket bay. The ligament lies outside and is curved, above a nymph.
The surface has 40 to 50 fine radial lines. They are most clearly developed towards the ventral and posterior edges. They are crossed by finer concentric lines and slightly more pronounced breaks in growth. This results in a fine grid-like pattern. The edge of the case is serrated, but the teeth do not necessarily correspond to the fine radial ribs; the serration is coarser. The color ranges from dark brown with white spots to a light shade of green.
The olive green to dark brown periostracum is thin and flakes easily, especially in juvenile specimens. It is dull and slightly glossy with microscopic fine concentric wrinkles. The solid shell is white with pale red-brown spots on the outside; there are brown spots on the inside, especially around the muscle impressions. The soft body is yellowish white with a light pink coat. The strong foot is long and tapering to a point.
Way of life, occurrence and distribution
The flat-ribbed cockle lives buried shallowly in silty-sandy to coarse-grained sediments from the tide line to a depth of 183 m. It is widespread from southern Norway to West Africa at the level of the Cape Verde Islands . It is also found in the waters around the Canary Islands , the Azores and Madeira, and in the Mediterranean. It also seems to live in the southern North Sea, although here the flaps washed ashore are mostly subfossil .
Taxonomy
The taxon was set up in 1791 by Johann Friedrich Gmelin . The species is now part of the genus Laevicardium .
supporting documents
literature
- Guido Poppe and Yoshihiro Goto: European Seashells Volume 2 (Scaphopoda, Bivalvia, Cephalopoda) . 221 pp., Verlag Christa Hemmen, Wiesbaden 1993 (2000 unc. Reprint) ISBN 3925919104
On-line
Individual evidence
- ↑ Poppe and Goto, p. 97
- ^ Johann Friedrich Gmelin: Caroli a Linné, systema naturae. Tom. I. Pars VI. Pp. 3021–3910, Lipsia / Leipzig, Beer 1791. Online at www.biodiversitylibrary.org (p. 3254)
- ↑ MolluscaBase: Laevicardium crassum (Gmelin, 1791)
