(Linné, 1758)

Description:
Shell elongate, oblong, or irregular, umbones anterior to midline. Sculpture of about ten thin, concentric ridges, raised and convoluted, conspicuous posteriorly where they form distinct frills. Fine radiating ridges visible between the concentric sculpture. Growth stages are indistinct. Lunule is obscured, escutcheon elongate, narrow, most prominent on the left valve. Three cardinal teeth in each valve; centre one of the left valve, centre and posterior of right, bifid. Adductor scars and pallial line are distinct. Pallial sinus is short, U-shaped (I. irus).

Size:
Up to 25 mm long.

Colour:
Yellowish white or fawn, usually darker about the umbones. Inner surfaces are white, with blue or chestnut patches. particularly posteriorly.

Animal:
The animal is white, tinged with pink. The siphons are united for half of their length, and the valve of the lower is protruded beyond the fringe. The foot is rather small, compressed, and adapted for spinning a byssus(I. irus-animal).

Habitat:
In holes and crevices in rock, or in Laminaria holdfasts, from the lower shore into the shallow sublittoral.

Distribution:
In British Isles southern and western coasts only. Ranges south to the Mediterranean and West Africa.

Kingdom Animalia
Phylum Mollusca
Class Bivalvia
Subclass Heterodonta
Order Veneroida
Family Veneridae
Genus Irus
Species Irus irus

Status in World Register of Marine Species

Accepted name: Irus irus (Linnaeus, 1758)

Scientific synonyms and common names

Donax irus Linné, 1758
Tellina cornubiensis Pennant, 1777
Cuneus foliatus da Costa, 1778
Venus bottarii Renier, 1804
Venerupis irus var. barrensis de Gregorio, 1889
Venerupis irusiana Locard, 1892
Venerupis irus var. bicolor B.D.D., 1893
Venerupis irus var. crebrilamellata B.D.D., 1893
Venerupis irus var. flava B.D.D., 1893
Venerupis irus var. tricolor B.D.D., 1893
Venerupis irus var. rosea B.D.D., 1893
Venerupis irus var. geographica Monterosato, 1917
Notirus irus

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.

Poppe, G.T. & Y. Goto, 1993. European Seashells. Vol. II. 221 pp. Wiesbaden/Verlag Christa Hemmen.

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.

You can continue searching for Irus irus on one of these Web sites:

Fauna Europaea (animals) | IOPI (plants) | NCBI (genetic)

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