Black bean clam
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Black bean clam ( niger muscle ) |
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| ( Gray , 1824) |
The black bean clam ( Musculus niger ) is a type of clam from the mussel family (Mytilidae).
features
The casing is roughly egg-shaped with a strongly arched dorsal edge and a weakly arched ventral edge. It becomes up to about five centimeters long, in exceptional cases up to seven centimeters. The vertebra is near the front end. The anterior sphincter impression is long, narrow and curved, the posterior sphincter is significantly larger and wider. The surface line is not indented. The lock has no teeth. Two radial fields emanate from the vertebra, a front and a rear field. The front panel has 20 to 25 radial ribs and the rear panel has 40 to 60 radial ribs. The edge of the case is notched in the area of the rib panels. The border between the non-ribbed middle field and the rear ribbed field is not sharply defined. The growth strips are only weakly developed. The periostracum is yellowish in juvenile specimens, with age it becomes increasingly darker brown to almost black. If the periostracum is removed, the skin is yellow to purple-brown. The mother-of-pearl inside is dark blue to purple in color, weathered flaps have a silvery sheen on the inside.
Similar species
The black bean clam is significantly larger than the green bean clam ( Musculus discors ) and the marbled bean clam ( Modiolarca marmorata ). The vertebra of the black bean clam is not as far at the front end as the vertebra in the two species mentioned. In contrast to the green bean clam, the transition from the middle to the rear field is not keel-like. There are more ribs in both the anterior and posterior costal areas.
Geographical distribution and way of life
The black bean clam occurs on the fringes of the North Atlantic and North Pacific. The mussels live there on sandy silt or silty sand soils from about 7 meters water depth to about 90 meters water depth. They are also found in the North Sea, there up to about 75 meters water depth, and in the western Baltic Sea, here from about 10 meters to 28 meters water depth.
The animals anchor themselves to stones or algae with byssus threads. Older specimens in particular are literally wrapped in a weave of linen.
development
The eggs are not released into the open water, but are wrapped in gelatinous egg cords and placed in a structure made of byssus threads. The eggs measure 0.52 × 0.36 mm and are very rich in yolks. No free-swimming larvae are formed, but the juvenile mussels quickly return to life on the ground after leaving the egg lines.
Taxonomy
The taxon was introduced to scientific literature in 1824 by John Edward Gray as Modiola nigra . However, he gave no description of the new taxon, but referred to two older works. The World Register of Marine Species lists the taxon as a valid species.
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. 227)
- 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. 35)
- 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. 51)
- Rainer Willmann: Mussels and snails of the North and Baltic Seas. 310 p., Neumann-Neudamm, Melsungen 1989, ISBN 3-7888-0555-2 (p. 102)
Individual evidence
- ^ Mary Ann Gilbert: The Discordant Mussel (Musculus Discors) and the Little Black Mussel (Musculus Niger) in Maine and Their Relevance to the Critical Areas Program. 26 p., Maine State Planning Office, 1977 snippet at Google Books
- ↑ John Edward Gray: Shells. In: Parry WE (Ed.): Supplement to Appendix, Parry's Voyage for the Discovery of a north-west passage in the years 1819-1820, contaning an account of the subjects of Natural History. London: John Murray Appendix 10, Zool .: 240–246, 1824 Online at www.biodiversitylibrary.org (S.CCXLIV = 244)
- ^ World Register of Marine Species
