Nut shells

Nut shells
Acila cobboldiae
Systematics
Sub-stem : Shell molluscs (Conchifera) Class : Mussels (Bivalvia) Subclass : Protobranchia Order : Nuculida Superfamily : Nuculoidea Family : Nut shells
Scientific name
Nuculidae
Gray , 1824

The nut clams (Nuculidae) are a family of the superfamily Nuculoidea within the order of the Nuculida . The oldest representatives of the nut shells have been traced back to the Silurian .

features

The nut shell family includes species with a small shell that is only centimeters in size. The front end is well rounded, the rear end can be trimmed, which means that the housing is often triangular or beaked in outline. The vertebra is usually located behind the middle. 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 bar, with more teeth (up to approx. 30) being formed in the front lock part than in the rear lock part (about 10 to 20). The solid shell consists of three aragonitic layers and the organic periostracum . The two sphincters are both equally strong, the nut shells have no siphons , and the surface line is not indented. They also have no byssus gland . The wide foot is reminiscent of the crawl sole of some snails.

Geographical distribution, habitat and way of life

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

The nut shells live largely buried in the soft sediment. They are predominantly detritus eaters. The respiratory water is transported into the mantle cavity by means of cilia and filtered between the gills. However, these food particles only represent the smaller part of the animals' food. The greater part of the food is taken in through the pair of mouth flap buttons fitted with eyelashes. The probes are moved over the surface of the sediment and the food particles (detritus) are brought to the mouth by the movement of the eyelashes.

The development of the nut shells is always yolk-rich, i. H. the eggs contain a large supply of yolks. Most species develop a special form of larvae, the so-called Pericalymma larva, which does not consume any food (plankton). After about two weeks, the larva changes to soil life and metamorphosis. In addition, only a Prodissoconch I is formed, which is followed by the juvenile housing.

Taxonomy

The taxon was set up in 1824 by John Edward Gray . The World Register of Marine Species and the Paleobiology Database add the following genera to the family.

• Nut clams family (Nuculidae Gray, 1824)
  • Subfamily Nuculinae Gray, 1824
    • Acila H. Adams & A. Adams, 1858
    • Gibbonucula Eames, 1951
    • Lamellinucula Schenck, 1944
    • Linucula Marwick, 1931
    • Nucula Lamarck, 1799
    • † Pectinucula Quenstedt, 1930
    • Pronucula Hedley, 1902
  • Subfamily Nuculominae Maxwell, 1988
    • Brevinucula Thiele, 1934
    • Economolopsis Hoare, Heaney & Mapes, 1989
    • † Leionucula Quenstedt, 1930
    • † Nuculoidea HS Williams & Breger, 1916
    • † Nuculoma Cossmann, 1907
    • † Nuculopsis Girty, 1911
  • Subfamily Palaeonuculinae Carter, 2001
    • Condylonucula DR Moore, 1977
    • † Palaeonucula Quenstedt, 1930
  • Incerta Subfamilia
    • Austronucula Powell, 1939
      • Austronucula perminima (Monterosato, 1875)
    • † Dacromya Agassiz, 1840
    • Ennucula Iredale, 1931
    • Microgloma Saunders and Allen, 1973
    • Neonucula Lan & Lee, 2001
    • † Nuculanella Tasch, 1953
    • † Nuculavus Chernyshev, 1943
    • Rumptunucula Bergmans, 1978
    • † Similiconcha Zhang, 1977
    • Sinonucula Xu, 1985
    • † Trigonucula Ichikawa 1949
    • Varinucula Maxwell, 1988

supporting documents

literature

• Michael Amler, Rudolf Fischer & Nicole Rogalla: Mussels. Haeckel library, Volume 5. Enke Verlag, Stuttgart 2000, ISBN 3-13-118391-8 .
• Rüdiger Bieler & Paula M. Mikkelsen: Bivalvia - a look at the branches . Zoological Journal of the Linnean Society, 148: 223-235, London 2006.
• Joseph G. Carter: Shell and ligament microstructure of selected Silurian and Recent palaeotaxodonts (Mollusca: Bivalvia). American Malacological Bulletin, 16: 217-238, 2001 ( online at biostor.org )

Individual evidence

1. ↑ Rudolf S. Scheltema, Isabelle P. Williams: Reproduction among protobranch bivalves of the family Nuculidae from sublittoral, bathyal, and abyssal depths off the New England coast of North America. Deep-Sea Research II, 56: 1835-1846, 2009 doi : 10.1016 / j.dsr2.2009.05.024
2. ↑ John Edward Gray: Shells. In: WE Parry (Ed.): Supplement to the Appendix of Captain Parry's Voyage for the Discovery of a North-West Passage in the Years 1819-20. Containing an Account of the Subjects of Natural History . S.CCXL-CCXLVI, London 1824. Online at www.biodiversitylibrary.org (S.CCXLI)
3. ^ World Register of Marine Species: Nuculidae Gray, 1824
4. ^ Paleobiology Database: Family Nuculidae Gray 1824
5. ↑ Krzysztof Hryniewicz, Crispin T, S. Little, Hans Arne Nakrem: Bivalves from the latest Jurassic-earliest Cretaceous hydrocarbon seep carbonates from central Spitsbergen, Svalbard. Zootaxa, 3859 (1): 001-066, 2014 PDF

Web links

Commons : Nuculidae  - Collection of images, videos, and audio files