Thin-shelled nut shell
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Thin-shelled nut clam ( Ennucula tenuis ) |
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| Ennucula tenuis | ||||||||||||
| ( Montagu , 1808) |
The thin-shelled nut shell ( Ennucula tenuis ) is a shell - type from the family of nuculidae (Nuculidae).
features
The evenly folded, moderately inflated housing is up to about 1.3 cm long, it is approximately triangular to slightly elliptical or egg-shaped. It is slightly longer than it is tall, the height is about 75% of the length. The slightly swollen vertebra lies behind the middle, measured on the total length of the dorsal margin, about a fifth from the rear end. The anterior dorsal margin is very long, slopes moderately steeply and is slightly convex. The posterior dorsal margin is almost straight, only very slightly convex and slopes steeply. The transition from the posterior dorsal margin to the ventral margin is clearly angled, while the transition from the anterior dorsal margin is flatly rounded. The ventral margin is moderately deeply convex. The inner edge of the two flaps is not serrated. The lancet-shaped lunula is comparatively long with indistinct margins. The elongated heart-shaped area is slightly raised, but the edges are also indistinctly limited.
The lock or the lock strip is wide and angled (over 90 °). The similar teeth are comparatively long and pointed. In the section in front of the vertebra there are 16 to 18 teeth, in the section behind the vertebra 8 to 10 teeth. The internal ligament is opistodetic and triangular in shape. It sits on a well-developed resilifer . A thin and barely visible ligament also lies externally and in front of the vertebrae. The teeth extend beyond the tip of the resilifer.
The skin is comparatively thin, hence the name, but not fragile, and olive green or bluish green in color. It is made of mother-of-pearl . The surface shows fine, dense, somewhat irregular growth strips. Some, somewhat coarser concentric lines are also switched on, which can be interpreted as growth interruptions. The periostracum is greenish-yellow, yellowish, gray-yellow, brownish-yellow to brownish in color, the surface is shiny. Occasionally, slightly darker concentric bands also occur. The edge is also often a little darker.
The surface line is entire without indentation. The two sphincters are egg-shaped and almost the same size. The impressions of the muscles on the inside of the shell are not particularly clear.
Geographical distribution and habitat
The thin-shelled nut shell has a circumpolar distribution. In the eastern Atlantic it occurs from the Arctic to about Morocco , in the western Atlantic to about the height of Maryland . In the Pacific Ocean, the distribution area extends on the American west coast to the southern Gulf of California at the 22nd degree of latitude (north of the Marias Islands ), on the Asian Pacific coast to Japan ( Honshu ). It also penetrates the Mediterranean , the North Sea and the western Baltic Sea .
It lives on muddy and fine sand soils from about 10 to 700 meters water depth, in the Arctic up to 2,200 meters (north triangle).
Taxonomy
The taxon was first described in 1808 by George Montagu as Arca tenuis . In older publications it can be found in the combinations Nucula tenuis and Nuculoma tenuis . Today it belongs to the genus Ennucula Iredale, 1931.
supporting documents
literature
- S. Peter Dance, Rudo von Cosel (arrangement of the German edition): The great book of sea shells. 304 p., Verlag Eugen Ulmer, Stuttgart 1977, ISBN 3-8001-7000-0 (p. 222/3 as Nucula tenuis )
- 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. 3 as Lionucula tenuis )
- Guido Poppe and Yoshihiro Goto: European Seashells Volume 2 (Scaphopoda, Bivalvia, Cephalopoda) . 221 p., Verlag Christa Hemmen, Wiesbaden 1993 (2000 unc. Reprint), ISBN 3925919104 (p. 37 as Nucula tenuis )
- Rainer Willmann: Mussels and snails of the North and Baltic Seas. 310 p., Neumann-Neudamm, Melsungen 1989, ISBN 3-7888-0555-2 (p. 82 as Nucula tenuis )
Individual evidence
- ↑ Pablo Zamorano, Michel E. Hendrickx, Arturo Toledano-Granados: New geographic and depth records for deep-water mollusks in the Gulf of California, Mexico. Revista Mexicana de Biodiversidad, 78: 311-318, 2007 PDF
- ↑ George Montagu: Supplement to Testacea Britannica. SI-V, 1-183, London, J. White, 1808. Online at www.biodiversitylibrary.org
- ↑ World Register of Marine Species: Ennucula tenuis (Montagu, 1808)
