Nucula

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Nucula
Large nut clam (Nucula nucleus)

Large nut clam ( Nucula nucleus )

Systematics
Subclass : Protobranchia
Order : Nuculida
Superfamily : Nuculoidea
Family : Nut clams (Nuculidae)
Subfamily : Nuculinae
Genre : Nucula
Scientific name
Nucula
Lamarck , 1799

Nucula is a clam genus of the family of nuculidae (Nuculidae) in the order of Nuculida . The genus has beenknownsince the Cretaceous .

features

The casing of the Nucula species is usually small (a few centimeters) and roughly triangular. The front end is well rounded, the rear end trimmed. The vertebra sits behind the center. The rear end of the ventral margin is usually angled. The ligament is sunk, it divides the lock into a front and back part. The lock is angled, the angle is about 90 ° or a little more. The lock consists of similar, elongated teeth and pits perpendicular to the lock line, with more teeth (up to approx. 30) being formed in the front part of the lock than in the rear part (about 10 to 20). The solid shell consists of three aragonitic layers, an inner layer with platelet arranged mother -of- pearl plates, a middle layer with columnar arranged mother-of-pearl leaves and an outer layer with prismatic-denticular structures and the organic periostracum . The edge of the housing is finely indented due to the prismatic-dental structures. The surface shows fine concentric growth lines and very fine radial lines that are barely visible to the naked eye. The surface line is not indented, there are no siphons. The rear and front sphincters are roughly the same size.

Geographical distribution and habitat

The species of the genus Nucula occur worldwide in all seas. They mostly live in muddy and fine sandy soils from the shallow subtidal to greater sea depths (over 3000 meters).

Taxonomy

The taxon was established by Lamarck in 1799. Arca nucleus Linné, 1758 is the type species by monotype. Nucula is the type genus of the subfamily and family Nuculinae or Nuculidae Gray, 1824. The World Register of Marine Species currently lists almost 90 recent species

In addition, there is a still unknown number of fossil 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. 222)
  • Rudolf Kilias: Lexicon marine mussels and snails. 2nd edition, 340 p., Verlag Eugen Ulmer, Stuttgart 1997 ISBN 3-8001-7332-8 (p. 219)
  • Raymond C. Moore : Treatise on Invertebrate Paleontology. Part N: Mollusca. 6, Bivalvia. Vol. 2. The University of Kansas et al., Boulder CO 1969 (S.N230 / 1)
  • 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. 4)

Individual evidence

  1. ↑ Jean-Baptiste de Lamarck: Prodrome d'une nouvelle classification des coquilles, comprenant une rédaction appropriée des caractères génériques, et l'établissement d'un grand nombre de genres nouveaux. Mémoires de la Société d'Histoire Naturelle de Paris, 1: 63-91, Paris, 1799 Online at www.biodiversitylibrary.org (p. 87).
  2. ^ A b World Register of Marine Species: Nucula Lamarck, 1799

Web links

Commons : Nucula  - collection of images, videos and audio files