Common scallop shell

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Common scallop shell
Common scallop (Thyasira flexuosa)

Common scallop ( Thyasira flexuosa )

Systematics
Superordinate : Imparidentia
Order : Lucinoida
Superfamily : Thyasiroid
Family : Thyasiridae
Genre : Thyasira
Type : Common scallop shell
Scientific name
Thyasira flexuosa
( Montagu , 1803)

The common folded mussel ( Thyasira flexuosa ) is a type of mussel from the Thyasiridae family . The species lives in symbiosis with thiotrophic (sulfide-oxidizing) bacteria in the gills.

features

The equally-flattened, moderately inflated cases are rounded to ovoid in outline, usually slightly higher than long. They reach a maximum length of 1.2 to 1.5 centimeters. The housings are unequal, the vertebrae sit in front of the middle and are twisted forward. The anterior dorsal margin is slightly concave. The posterior dorsal margin is convex. The transition from the dorsal margin to the posterior margin is slightly ear-shaped, with a straight or almost slightly concavely curved section just before the transition to the ventral margin. The ventral margin is deeply convex. The rear part of the housing has two radial folds, the inner fold runs approximately to the transition from the rear dorsal edge to the ventral edge and is more pronounced than the outer fold which runs to the transition from the rear edge to the ventral edge. The posterior dorsal margin is clearly indented between the two folds. The heart-shaped lunula is sunk and clearly demarcated. The narrow area can also be clearly seen. The lock is without proper teeth. In the right flap, instead of a cardinal tooth, there is only a small inconspicuous peg that engages in a corresponding pit in the left flap. The surface line is entire, there are no siphons. The two sphincter impressions are only weakly developed; the anterior sphincter impression is elongated, the posterior rather rounded.

The surface shows fine concentric growth lines, the inside edge of the housing is smooth. However, the growth lines are very irregular with occasional notches and thickenings. The skin is thin and whitish-translucent. The periostracum is thin and decrepit; it wears off quickly. The surface is often covered with iron crusts. The larval housing (Prodissoconch) measures 160 to 180 µm in diameter (or length).

Geographical distribution and way of life

The species is circumpolar. In the eastern North Atlantic, the distribution area extends in the south to the Mediterranean Sea and the Canary Islands . In the western North Atlantic it occurs southwards into the Gulf of Mexico. It lives from shallow water (around four meters) to a depth of 2,000 meters in oxygen-poor and sulfide-rich muddy soils.

Thyasira flexuosa digs a tube to the surface of the sediment with its foot. The walls of the tube are solidified with mucus that is produced by glands in the foot. The food is poured in through the tube. The inflow and outflow openings are located at the rear end of the housing. There may be many other tubes under the case. Sulfur-oxidizing bacteria live on the gills.

Taxonomy

The species was established in 1803 by George Montagu as Tellina flexuosa . It is now generally recognized in the genus Thyasira Lamarck, 1818.

supporting documents

literature

  • 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. 78/9)
  • Guido Poppe. Yoshihiro Goto: European Seashells Volume 2 (Scaphopoda, Bivalvia, Cephalopoda) . 221 p., Verlag Christa Hemmen, Wiesbaden 1993 (2000 unc.Reprinted ), ISBN 3925919104 (p. 83)
  • Rainer Willmann: Mussels and snails of the North and Baltic Seas. 310 pp., Neumann-Neudamm, Melsungen 1989, ISBN 3-7888-0555-2 (p. 115)

Individual evidence

  1. ↑ Daniel L. Distel, Ann P. Wood: Characterization of the Gill Symbiont of Thyasira flexuosa (Thyasiridae: Bivalvia) by Use of Polymerase Chain Reaction and 16S rRNA Sequence Analysis. Journal of Bacteriology, 174 (19): 6317-6320, 1992
  2. ↑ Georg Montagu: Testacea Britannica, or natural history of British shells, marine, land, and fresh-water, including the most minute: systematically arranged and embellished with figures. P. I-XXXVII, 1-606, London, White 1803. Online at www.biodiversitylibrary.org (P. 72)
  3. ↑ MolluscaBase: Thyasira flexuosa (Montagu, 1803)

Web links

Commons : Common Folded Clam ( Thyasira flexuosa )  - Collection of images, videos, and audio files