Cardioidea

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Cardioidea
Lagoon cockle (Cerastoderma glaucum)

Lagoon cockle ( Cerastoderma glaucum )

Systematics
Class : Bivalvia
Subclass : Heterodonta
Euheterodonta
Superordinate : Imparidentia
Order : Cardiida
Superfamily : Cardioidea
Scientific name
Cardioidea
Lamarck , 1809

The Cardioidea are a superfamily of mussels from the order Cardiida . It occurs for the first time in the Upper Triassic .

features

The housings, which have the same flaps, are often very inflated, are very small to very large. The Cardioidea superfamily also includes the largest known mussels today ( Tridacna gigas , up to 1.4 m). The outline is rounded, transverse, high or oblique-egg-shaped, or rounded-triangular. They are equilateral or almost equilateral, the vertebrae, which are usually curled forward, rarely also perpendicular to the longitudinal axis of the housing, are usually located near the center line. They are often prominent and bloated. The heterodontic lock has two short, somewhat bulky main teeth and one to three strong side teeth. The external ligament lies on nymphs behind the vertebrae. The sphincters are almost the same size or the anterior sphincter is reduced. The surface line is not or only slightly indented.

The aragonitic shell is usually strong and solid, extremely thick and massive ( Tridacna ), rarely also thin and translucent or with window-like structures ( Corculum ). It consists of an outer layer with crossed lamellas and inner layers with complex crossed lamellas. The ornamentation usually consists of radial ribs of different strength, thickness and number, which are often occupied with knots, scales or thorns. The periostracum is usually thin.

The siphons are short. The foot is usually long and strong; some forms have a byssus even in the adult stage .

Geographical distribution, habitat and way of life

The superfamily is common worldwide. Most species live shallowly buried in sandy, fine sandy or silty soils in shallower water. The few species of the genera Corculum and Tridacna have endosymbiotic dinoflagellates .

Taxonomy

The superfamily Cardiidae was set up by Jean-Baptiste de Lamarck in 1809 as Les cardiadées . Since the name was ascribed to Lamarck in the later Latinization, Lamarck is also considered the author of the taxon in the more recent scientific literature. The name is thus available as a superfamily name, family name and subfamily name as well as a tribe name. Some authors still subdivide the family into subfamilies: Currently there is a subdivision into two families:

literature

  • Michael Amler, Rudolf Fischer & Nicole Rogalla: Mussels . 214 pp., Haeckel-Bücherei, Volume 5. Enke Verlag, Stuttgart 2000 ISBN 3-13-118391-8 (pp. 105/6)

Individual evidence

  1. ^ Jean-Baptiste de Lamarck: Philosophy zoologique. Vol. 1, XXV + 428 S., Dentu, Paris, 1809 Online at Google Books (p. 318).
  2. ^ MolluscaBase: Cardioidea