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

Humpback scallop (Talochlamys pusio)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.
Only coastal and marine records shown



Chlamys distorta is a small bivalve, up to 5 cm long, often with a brightly patterned and coloured shell. The valves are oval with 60 (35-50 in juveniles) or more radiating ribs and two prominent ears, one of which is larger than the other. Once an individual has become cemented to a hard surface, the lower (right) valve becomes deeply convex whereas the upper (left) valve is less so.

Recorded distribution in Britain and Ireland

Common on all coasts of Britain and Ireland.

Global distribution



Attached to hard substrata from the low shore to at least 100 m depth.

Depth range


Identifying features

  • Valves with well developed ears.
  • Right anterior ear indented with a byssal notch.
  • Inequivalve: right (lower) valve more deeply convex than the left (upper) valve.
  • 60 or more radiating ribs in the part of the shell nearest the margins.

Additional information

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Listed by

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Further information sources

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  1. Gibson, R., Hextall, B. & Rogers, A., 2001. Photographic guide to the sea and seashore life of Britain and north-west Europe. Oxford: Oxford University Press.

  2. Hayward, P.J. & Ryland, J.S. 1990. The marine fauna of the British Isles and north-west Europe. Oxford: Oxford University Press.

  3. Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]

  4. National Biodiversity Network (NBN) Atlas website. Available from:  Accessed 01 April 2017

  5. Picton, B.E. & Costello, M.J., 1998. BioMar biotope viewer: a guide to marine habitats, fauna and flora of Britain and Ireland. [CD-ROM] Environmental Sciences Unit, Trinity College, Dublin.

  6. Tebble, N., 1966. British Bivalve Seashells. A Handbook for Identification, 2nd ed. Edinburgh: British Museum (Natural History), Her Majesty's Stationary Office.


This review can be cited as:

Neal, K.J. 2004. Talochlamys pusio Humpback scallop. 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 16-08-2018]. Available from:

Last Updated: 14/06/2004