Common clam
| Common clam | ||||||||||||
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Common clam ( Chamelea gallina ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Chamelea gallina | ||||||||||||
| ( Linnaeus , 1758) |
The common clam ( Chamelea gallina ) is a species of clam from the family of clams (Veneridae) in the order of the Venerida .
features
The equally-folded, moderately inflated housing is up to about 5 cm long. It is oblique-triangular in outline with rounded front and rear ends. It is slightly unequal, with the vertebrae in front of the midline. The posterior dorsal margin is long, almost straight and extends to the posterior, rounded posterior end. The heart-shaped lunula is clearly delimited and has radial longitudinal ridges. The sunk area , on the other hand, is only indistinct. The ligament is sunk, sits on the inner groin and extends up to a third of the length of the posterior dorsal margin. The lock consists of three cardinal teeth in each flap. Lateral teeth are missing. The jacket bay is relatively short and triangular in shape. The posterior sphincter is slightly thicker than the anterior sphincter.
The skin is whitish to pale yellow and thick-skinned. The ornamentation consists of flat and smooth, concentric ribs that are not exactly parallel to the edge. The inner edge is finely grained. The periostracum is shiny. A pattern of fine, brown, radial rays or zigzags is formed on the surface. The inside is white. The posterior end, and sometimes the ventral zone, can be colored purple. In contrast, the vertebral region is often tinted pink.
Similar species
On average, the common clam with a shell length of about 5 cm is significantly larger compared to the very similar striped clam ( Chamelea striatula ) with a length of 2 to 3 cm (very rarely up to 4.5 cm in length). The posterior end of the striped clam tapers, the posterior dorsal margin and the area are relatively longer and only slightly curved. The mantle bay is deeper and tapering to a point. The surface does not shine and the ribs parallel to the edge are somewhat narrower. However, both shapes are somewhat variable in terms of the shape of the case and the ornamentation. With the specified differences, 80 to 95% of the specimens can be safely assigned to one of the two species, depending on the characteristic. The pallial index length of the jacket bay and the housing length allows a reliable differentiation.
Geographical distribution, habitat and way of life
The range of the common clam stretches from the Black Sea , across the Mediterranean Sea to southern Portugal . There the striped clam ( Chamelea striatula ) and the common clam appear sympetrically .
The animals live from the tidal range to about 20 meters water depth and prefer muddy-sandy to sandy soils. They are epibenthonic filter feeders.
development
The species is segregated. The animals become sexually mature at a size of 8 to 14 millimeters. The sex products in populations in the Algarve are released from June to September in a coordinated manner between the sexes into the open water, where fertilization takes place. Here the animals live up to five years, usually three to four years. In the Adriatic and also in the Marmara Sea and the Black Sea, the specimens are older (eight to nine years).
Taxonomy
The taxon was established by Carl von Linné in 1758 . It is the type species of the genus Chamelea Mörch, 1853. The taxon is now generally accepted as a valid taxon. However, there are still authors who consider the closely related striped clam a more recent synonym or just a subspecies of the common clam. However, the sympatric occurrence of both species in the western Mediterranean and the Algarve speaks against this assumption. The MolluscaBase lists the following synonyms: Chione schottii Dall, 1902, Venus corrugatula Krynicki, 1837, Venus gallina var. Alba Bucquoy, Dautzenberg & Dollfus, 1893, Venus gallina var. Articulata Pallary, 1900, Venus corrugatula Krynicki, 1837, Venus gallina var. flava Bucquoy, Dautzenberg & Dollfus, 1893, Venus gallina var. major Bucquoy, Dautzenberg & Dollfus, 1893, Venus gallina var. minor Bucquoy, Dautzenberg & Dollfus, 1893, Venus nucleus Statuti, 1880, Venus nuculata Locard, 1892 and Venus sinuata Born , 1778.
Commercial importance
The common clam is an important seafood in the Mediterranean. The mussels are fished with dredges and bottom trolls. The catches vary from year to year and in years after 2000 they fluctuated between about 30,000 tons to almost 80,000 tons per year. The largest catches are made in Italy.
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. 269)
- 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. 115.
- Guido Poppe. Yoshihiro Goto: European Seashells Volume 2 (Scaphopoda, Bivalvia, Cephalopoda) . 221 pp., Verlag Christa Hemmen, Wiesbaden 1993 (2000 unc. reprint), ISBN 3925919104 (p. 120)
Individual evidence
- ↑ Marta M. Rufino, Miguel B. Gaspar, Alexandre M. Pereira, Paulo Vasconcelos: Use of shape to distinguish Chamelea gallina and Chamelea striatula (Bivalvia: Veneridae): Linear and geometric morphometric methods. Journal of Morphology, 267 (12): 1433-1440, 2006 doi : 10.1002 / jmor.10489
- ↑ Miguel B. Gaspar, Alexandre M. Pereira, Paulo Vasconcelos, Carlos C. Monteiro: Age and growth of Chamelea gallina from the Algarve coast (southern Portugal): Influence of seawater temperature and gametogenic cycle on growth rate. Journal of Molluscan Studies, 70: 371-377, 2004.
- ↑ NA Boltacheva, SA Mazlumyan: The growth and longevity of Chamelea gallina (Mollusca, Veneridae) in the Black Sea. Vestnick Zoologii, 37 (3): 71-74, 2003 PDF
- ^ Carl von Linné: Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. Pp. 1-824, Holmia / Stockholm, Salvius, 1758. Online at www.biodiversitylibrary.org (p. 685).
- ↑ a b MolluscaBase: Chamelea gallina (Linnaeus, 1758)
- ↑ FAO Fisheries and Aquaculture Department: Species Fact Sheets Chamelea gallina (Linnaeus, 1758) (here the striped clam and the common clam are counted as one species!)
