Dwarf Tell Clam
| Dwarf Tell Clam | ||||||||||||
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Dwarf Tell Clam ( Asbjornsenia pygmaea ) |
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| Scientific name | ||||||||||||
| Asbjornsenia pygmaea | ||||||||||||
| ( Lovén , 1847) |
The dwarf tell mussel ( Asbjornsenia pygmaea ) is a type of mussel from the family of tell mussels (Tellinidae). It also occurs in the North Sea .
features
The comparatively small, moderately flattened case is slightly unevenly hinged and is up to 10 millimeters long. The right flap is slightly more arched than the left flap. The vertebrae sit well behind the midline, about a quarter (the length of the case) from the rear end. The small vertebrae are rolled up obliquely inwards (opisthogyr). The housing is elongated-egg-shaped with a slightly pointed rear end. The rear end of the case is bent slightly to the right. The length / width ratio is about 1.5. The anterior dorsal margin is straight and slopes down gently to the well-rounded anterior end. The posterior dorsal margin is even slightly concave and drops off steeply to the more rounded posterior end. The ventral margin is well rounded.
The ligament is a brown band that extends behind the vertebrae on an internal ridge (nymph) over half the length of the posterior dorsal margin. The lock plate is narrow. There are two cardinal teeth in each of the two valves. In the left valve the anterior cardinal tooth is grooved lengthways and two-pointed, the posterior cardinal tooth is only very weakly developed. In the right valve, on the other hand, the posterior cardinal tooth is longitudinally furrowed and two-pointed, and the anterior cardinal tooth is small (er). In the left valve, weak anterior and posterior lateral teeth are developed. In the right valve, however, the anterior and posterior lateral teeth are strongly developed. The base (or inner end) of the anterior lateral tooth extends to the base of the posterior cardinal tooth. The coat is indented very deeply beyond the center line. The lower edge of the jacket bay coincides with the ventral jacket edge. There are two sphincters; the anterior sphincter is slightly larger than the posterior sphincter.
The shell is thin-walled and fragile. The color palette ranges from whitish, yellowish, orange-red, pink to red-brown, often with somewhat darker bands running parallel to the edge, and rarely also radial fields. The inside of the shell is similarly colored. The surface shows only fine strips of growth parallel to the edge at regular intervals. The inside edge of the housing is smooth. The periostracum is a thin, silky, shiny coating, but is rarely preserved.
The foot is quite strong. The siphons are very long, flexible and not grown together. The two gills are unequal in size. The mouth lobes are well developed. The edge of the coat is pulled out to fringes.
Similar species
The elongated Tell mussel ( Moerella donacina ) is usually much larger. The posterior ventral side is straight. The coat is indented a little deeper. On the outside, it shows regularly radial color patterns (spots or interrupted bands).
Geographical distribution, habitat and way of life
The distribution area of the dwarf tell mussel extends from northern Norway (at about 70 ° north latitude) to the Ivory Coast , Guinea and the Cape Verde Islands . It also penetrates the North Sea and the Mediterranean.
The dwarf tell mussel prefers sandy and gravelly soils from below the low water line to about 150 meters water depth. It lives buried up to 15 cm deep in the sand. It lies on the left flap and extends the long siphons to the sediment surface (therefore the rear end is slightly curved to the right). When the tide comes in, it digs a little closer to the surface. It feeds on organic detritus because it absorbs with the mobile (inflow) siphon.
Taxonomy
The species name was proposed by Sven Lovén in 1847 . Occasionally the name Tellina pusilla Philippi, 1836, can still be found in the literature . This older synonym was preoccupied by Tellina pusilla Lamarck, 1806, and is therefore invalid. The species is now part of the genus Asbjornsenia Friele, 1886.
supporting documents
literature
- Fritz Gosselck, Alexander Darr, Jürgen HJ Jungbluth, Michael Zettler: common names for mollusks of the sea and brackish water in Germany. Mollusca, 27 (1): 3–32, 2009 PDF (p. 26 as Tellina pygmaea )
- Fritz Nordsieck: The European sea shells (Bivalvia). From the Arctic Ocean to Cape Verde, the Mediterranean Sea and the Black Sea. 256 p., Gustav Fischer Verlag, Stuttgart 1969 (p. 131 as Moerella pusilla )
- Guido Poppe. Yoshihiro Goto: European Seashells Volume 2 (Scaphopoda, Bivalvia, Cephalopoda) . 221 pp., Verlag Christa Hemmen, Wiesbaden 1993 (2000 unc. Reprint), ISBN 3925919104 (p. 112 as Tellina pusilla )
- Rainer Willmann: Mussels of the North and Baltic Seas. 310 p., Neumann-Neudamm, Melsungen 1989 ISBN 3-7888-0555-2 (p. 164/5)
- Paul Chambers: Channel Island Marine Molluscs: An Illustrated Guide to the seashells of Jersey, Guernsey, Alderney, Sark and Herm. 321 S., Charonia Media, 2008 ISBN 978-0-9560655-0-6 Online at Google Books (p. 250)
On-line
- Marine Bivalve Shells of the British Isles: Tellina (Moerella) pygmaea Lovén, 1846 (site of the National Museum Wales, Department of Natural Sciences, Cardiff)
- Marine Species Identification Portal: Tellina pygmaea Lovén, 1846
Individual evidence
- ^ Sven Lovén: Nordens Hafs-Mollusker. Öfversigt af Kongl. Vetenskaps-akademiens förhandlingar, 3 (for 1846): 182–204, Stockholm 1847 Online at www.biodiversitylibrary.org (p. 196)
- ↑ MolluscaBase: Asbjornsenia pygmaea (Lovén, 1846)
