information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

Chequered carpet shell (Ruditapes decussatus)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.



The shell of the chequered carpet shell is broadly oval or square in shape and is cream, yellowish, or light brown in colour, often with darker markings. The sculpture of the shell consists of concentric grooves and bold radiating ridges. There are quite distinct criss-cross (decussate) markings present posteriorly. When the valves are closed, below the beak there is a shallow, not particularly distinct, heart-shaped depression with light and dark brown fine radiating ridges. The beaks of one half of the valve are broadly oval in outline, with the line descending from the beak sharply curved; whilst the other side of the beak gradually curves. It can grow up to 7.5 cm in length. Each valve has three teeth, one on the left and two on the right which are bifid. The inside of the shell is polished white with an orange tint, occasionally with purple over a wide area below the umbones. The pallial line is u-shaped but does not extend beyond the mid-line of the shell.

Recorded distribution in Britain and Ireland

Mainly found off the southern and western coasts of Britain and around Ireland.

Global distribution

Found around the British Isles and western Europe, from the Mediterranean to west Africa.


This species tends to bury itself in sand, muddy gravel, or clay and is found on the lower shore and shallow sublittoral.

Depth range


Identifying features

  • The shell is cream, yellowish, or light brown in colour.
  • The sculpture of the shell consists of concentric grooves and radiating ridges creating a chequered appearance.
  • Criss-cross (decussate) markings posteriorly.
  • Can grow up to 7.5 cm.
  • Each valve has three teeth, one on the left valve and two on the right which are bifid.

Additional information

The chequered carpet shell is superficially similar in shape and size to the Manila clam Ruditapes philippinarum and to Venerupis senegalensis. The chequered carpet shell is distinguishable from the Manila clam by its very distinct radiating lines present on the shell and white foot, Ruditapes philippinarum is distinguishable by the distinctive black and white markings and orange foot. Venerupis senegalensis often has zigzag markings on the shell.

Listed by

- none -

Further information sources

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    This review can be cited as:

    Carter, M.C. 2003. Ruditapes decussatus Chequered carpet shell. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 21-09-2018]. Available from:

    Last Updated: 18/09/2003