Spoon clams

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Spoon clams
Fragile clam (Cochlodesma praetenue) (from GB Sowerby II, 1859: Plate 2, Fig. 10. [1])

Fragile spoon-mussel ( Cochlodesma praetenue ) (from GB Sowerby II, 1859: Plate 2, Fig. 10.)

Systematics
Subclass : Heterodonta
Euheterodonta
Superordinate : Anomalodesmata
Order :
Superfamily : Thracioidea
Family : Spoon clams
Scientific name
Periplomatidae
Dall , 1895

The spoon clams (Periplomatidae) are a family of clams . It is already known from the Upper Cretaceous. Currently (2016) about 45 species are assigned to this family.

features

The medium-sized cases are unevenly hinged, the right flap is larger and more arched (more bulbous) than the left flap, and towers above it. The housings are egg-shaped to oblong-egg-shaped in outline, the rear edge gapes. The vertebrae have a slot. The rear end can also be more or less pronounced, beak-like, elongated and truncated. The vertebrae are opisthogyr, orthogyr, or prosogyr. The lock is toothless.

The inner ligament sits on a spoon-shaped extension just below the vertebrae. Often there is also a small external ligament; it can also be absent. The lock is toothless. The mantle bay is usually wide and deep. The two sphincters are roughly the same size, but variable in outline, or even unequal in size. The siphons are separate and usually long. The foot is large and has no linen (any longer).

The skin is thin and aragonitic . The outer shell layer is granular-prismatic or columnar-prismatic, the inner layer mostly homogeneous or mother-of-pearl. The ornamentation consists of lines parallel to the edge, often somewhat irregular and coarser, or the surface is also almost smooth. In some species, there are strong radial ridges with depressions in between. The edge of the case is jagged ( Albimanus ).

Geographical distribution and habitat

The family is spread around the world. However, the focus of diversity is in the Indo-Pacific . The mussels live shallowly buried in muddy-sandy, sandy or fine gravel sediments.

Taxonomy

The taxon was established in 1895 by William Healey Dall as the family Periplomidae. However, the correct form is Periplomatidae. MolluscaBase assigns the following genera to the family:

supporting documents

literature

  • S. Peter Dance, Rudo von Cosel (arrangement of the German edition): The great book of sea shells. 304 pp., Verlag Eugen Ulmer, Stuttgart, 1977 ISBN 3-8001-7000-0 (p. 274)
  • Rudolf Kilias: Lexicon marine mussels and snails. 2nd edition, 340 p., Verlag Eugen Ulmer, Stuttgart 1997 ISBN 3-8001-7332-8 (p. 243)
  • Raymond Cecil Moore (Ed.): Treatise on invertebrate paleontology. Mollusca, 6, Part N, Bivalvia 2. XXXVIII S., S.N491-951, New York, 1969 (S.N849).
  • Guido Poppe and Yoshihiro Goto: European Seashells Volume 2 (Scaphopoda, Bivalvia, Cephalopoda) . 221 p., Verlag Christa Hemmen, Wiesbaden 1993 (2000 unaltered reprint), ISBN 3925919104 (p. 137)

Individual evidence

  1. ↑ George Brettingham Sowerby II : Illustrated index of British shells. containing figures of all the recent species, with names and other information. XV S., XXIV plate London, Simpkin, Marshall & Co., 1859 Online at www.biodiversitylibrary.org (plate 2)
  2. ↑ a b MolluscaBase: Periplomatidae Dall, 1895
  3. ^ William Healey Dall: Contributions to the Tertiary Fauna of Florida, with especial reference to the Miocene silex-beds of Tampa and the Pliocene beds of the Caloosahatchie River. Part 3. A new classification of the Pelecypoda. Transactions of the Wagner Free Institute of Philadelphia, 3 (3): 483-570, Philadelphia 1895 Online at www.biodiversitylibrary.org (p. 531)
  4. ↑ Paleobiology Database: † Aperiploma Habe 1952 (clam)

Web links

Commons : Spoon Clams (Periplomatidae)  - Collection of images, videos, and audio files