(Linné, 1758)

Description (shell):
Shell thin and brittle. Inequivalve; left valve more convex than right one. Equilateral with ears more or less equal; anterior ear of right valve slightly larger than posterior one, overlapping that of left valve and with a distinct fold along the hinge line, below it a small, rounded byssal notch, finely dentate along the lower edge. Ventral margin constituting more than a semicircle. Sculpture of about 20 bold, radiating ribs, finer ridges and concentric corrugated grooves, ears similarly sculptured; growth stages unclear; margin very crenulate (A. opercularis-drawing 2).

Size:
Up to 90 mm long, frequently less, as long as deep.

Colour:
Colour very variable: light pink to brown, orange, or yellow, usually marked with bands, zigzags, rays and spots of darker or lighter shades. Right valve often paler than left one, frequently with coloured markings on a creamy ground. (A. opercularis); (A. operculais-drawing).

Animal:
The animal is as varied in colour as the shell is. It lives attached by a byssus when small, later free and capable of swimming by the opening and rapid closing of the valves. The muscle for closing the valves is very large and powerful. The foot is developed as a finger-like organ, occupied in the spinning of byssal threads, which pass through the ears. The mantle margin is double, the inner finely fringed and the outer edged with long tentacles; at their base gleam a row of 35-40 black ocelli (eye-spots) which have a pupil-like spot of greenish grey. This species is much used for food.

Habitat:
Occurs in dense aggregations offshore to 100 m, occasionally between tidemarks; on sand and fine gravel.

Distribution:
Widespread and common in the North Sea (Distr. A. opercularis). Distributed from Norway south to the Mediterranean and Canary Isles.

Kingdom Animalia
Phylum Mollusca
Class Bivalvia
Subclass Pteromorphia
Order Pterioida
Family Pectinidae
Genus Aequipecten
Species Aequipecten opercularis

Status in World Register of Marine Species

Accepted name: Aequipecten opercularis (Linnaeus, 1758)

Scientific synonyms and common names

Ostrea opercularis Linné, 1758
Ostrea dubia Gmelin, 1791
Ostrea elegans Gmelin, 1791
Pecten audouinii Payraudeau, 1826
Pecten exasperatus Sowerby G.B. II, 1842
Pecten daucus Reeve, 1853
Pecten opercularis var. elongata Jeffreys, 1863 non Pecten elongatus Lamarck, 1819 non Pecten elongatus McCoy in Griffith, 1844
Pecten opercularis var. albovariegata Clement, 1875
Pecten lineatus var. albida Locard, 1888
Pecten lineatus var. bicolor Locard, 1888
Pecten opercularis var. depressa Locard, 1888
Pecten opercularis var. aspera B.D.D., 1889 non Pecten asper Lamarck, 1819 non Pecten asper Sowerby G.B. II, 1842
Pecten opercularis var. concolor B.D.D., 1889
Pecten heliacus Dall, 1925
Aequipecten bruei coeni Nordsieck, 1969 ; partim
Aequipecten bruei pulchricostatus Nordsieck, 1969
Chlamys opercularis

Hayward, P.J., Wigham, G.D. & N. Yonow, 1990. Mollusca I: Polyplacophora, Scaphopoda, and Gastropoda. In: The Marine Fauna of the British Isles and North-West Europe. (ed. P.J. Hayward & J.S. Ryland). Clarendon Press, Oxford: 628-730.

Jeffreys, J.G., 1869. British conchology. Vol. V -258 pp. Van Voorst, London.

Seaward, D.R., 1990. Distribution of the marine molluscs of north west Europe. Nature Conservancy Council.

Step, E., 1927. Shell life. 421 pp. Frederick Warne & Co., LTD, London.

Tebble, N., 1966. British Bivalve Seashells. 212 pp. Trustees of The British Museum (Natural history). London.

Wagner, H. P., 1991. Review of the European Pectinidae. Vitra Marina, 41(1): 1-48.

You can continue searching for Aequipecten opercularis on one of these Web sites:

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