White cockleshell
| White cockleshell | ||||||||||||
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Striarca lactea |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Striarca lactea | ||||||||||||
| ( Linnaeus , 1758) |
The white ark mussel ( Striarca lactea ) is a mussel species from the family Noetiidae in the order Arcida .
features
The equally flared, moderately inflated housing has a rounded, elongated trapezoid shape. The length of the adult housing is about 14 to 20 millimeters. The case is only slightly longer than it is tall (L / W index = 1.4), and the rear part of the case is slightly longer. The powerful vertebra is located two fifths of the total dorsal length from the anterior end. The vertebrae are low and wide and protrude over the almost straight, comparatively short dorsal margin. When viewed from above, the large eddies create a broad dorsal field.
The front edge drops off steeply (steeper than the rear edge) and is almost straight to slightly convexly rounded. The transition from the anterior dorsal margin to the anterior margin and also to the ventral margin are rounded flat. The transition from the posterior dorsal margin to the posterior margin is slightly rounded. The rear edge itself is almost straight or slightly convex; it falls flat (flatter than the front edge) to the ventral edge. The transition to the ventral margin is tightly rounded. The ventral margin is moderately deeply rounded. The rear housing field is clearly set off by a flat back starting from the vertebra and running to the transition from the rear to the ventral edge. In the ventral margin there is a recess for the byssus; Even when the housing is closed, the two flaps gape here. The inner edge of the case is essentially smooth, some specimens also show weak serrations that correlate with the radial ribs.
The lock is taxodont, the curved lock plate strong. The initially large teeth on the outside become smaller towards the middle. There are seven diverging teeth each in the back and front. The duplivincular ligament extends across the dorsal field in parallel ligaments.
The whitish skin is not particularly thick, but very robust. The ornamentation consists of radial, fine and dense ribs that are finely grained. The ribs on the rear and front housing fields are a little stronger and are further apart. They intersect with fine growth strips and somewhat more pronounced growth interruptions. As it continues to grow, secondary ribs interpose in between the primary ribs. The periostracum is mostly only preserved at the edge and in the rear part of the housing and is drawn out into dense, brown and short hairs between the fine ribs.
The two sphincters are roughly the same size. The muscle attachment points are slightly raised with a flat edge.
Geographical distribution, way of life and habitat
The species lives in the Mediterranean , Marmara and Black Sea, as well as the adjacent Atlantic coasts. In the north the distribution area extends to southern England, in the south along the African coast and the Canary Islands to Senegal . It occurs here from the tidal range to a depth of 270 meters.
It lives there attached to hard substrate with byssus threads, including other shell housings such as B. Cockles .
Taxonomy
Carl von Linné described the species for the first time in 1758 in the 10th edition of his Systema Naturae in the combination Arca lactea . It is the type species of the genus Striarca Conrad, 1862. Striarca lactea has a number of synonyms : Arca crinita Pulteney, 1799, Arca gaimardi Payraudeau, 1826, Arca lactanea SV Wood, 1840, Arca pennantiana Leach in Gray, 1852, Arca perforans Turton , 1819, Arca quoyi Payraudeau, 1826, Arca reticulata Risso, 1826, Arca rosea Nardo, 1847, Arca striata Reeve, 1844 (non Arca striata Gmelin, 1791), Arca striatella Nyst, 1848, Striarca lactea epetrima Oliver & Cosel, 1993 and Striarca lactea scoliosa Oliver & Cosel, 1993.
supporting documents
literature
- Rosina Fechter, Gerhard Falkner: Mollusks. 287 pp., Mosaik-Verlag, Munich 1990 (Steinbach's Nature Guide 10), ISBN 3-570-03414-3 , p. 76
- 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. 23 as Striarca (Galactella) lactea )
On-line
Individual evidence
- ^ Muzaffer Demir: Shells of Mollusca Collected from the Seas of Turkey. Turkish Journal of Zoology, 27: 101-140, 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, Holmiae / Stockholm, Salvius, 1758. Online at Göttinger Digitization Center (p. 694 as Arca lactea ).
- ↑ World Register of Marine Species: Striarca lactea (Linnaeus, 1758)
