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

Queen scallop (Aequipecten opercularis)

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



Both valves of the shell are convex. The outline is rounded with conspicuous ribs and projections, ears, on each valve. It can grow up to 9 cm in diameter. The shell is variable in colour but often light-pink to brown, orange or yellow and often with bands, zigzags, rays and spots of darker or lighter shades. The right valve is often paler and flatter than the left. The ears of the shell have fine ribs and concentric corrugations. The sculpture of the shell consists of approximately 20 bold, radiating ridges and the margins of the shell are strongly crenulate. When viewing the inside of the right valve (the more convex shell) the left (or anterior) ear is larger than the right. The left forms a notch below the ear and possesses small teeth. It is from this notch the young scallop release fine threads (the byssal thread) to attach to hard substrata. Spines are absent. The shell is often overgrown with encrusting sponge.

Recorded distribution in Britain and Ireland

Found around all British and Irish coasts.

Global distribution

Found south of Norway to the Mediterranean and the Canary Isles.


The queen scallop is found between tidemarks, to depths of 100 m and on sand or gravel, often in high densities. It also occurs amongst beds of horse mussels Modiolus modiolus.

Depth range


Identifying features

  • Shell variable in colour from pink, brown, orange or yellow with bands, zigzags, rays and spots.
  • Each valve has about 20 radiating ridges.
  • Grows up to 9 cm in diameter.
  • The anterior ear of the right valve is slightly larger than the left.

Additional information

Young scallops remain attached by the byssus, later becoming unattached and are then able to swim freely. The queen scallop differs from the king scallop Pecten maximus. In the king scallop, the lower valve on which it lies, is deeply convex and white, while the upper valve, generally red or brown (often marbled) is almost flat. In the queen scallop, both valves are convex, the upper being slightly more-so than the right and colour is variable. The number of ribs varies between species with the queen scallop possessing 19 to 22 ribs and the king scallop 15 to 17 ribs. The queen scallop is fished commercially at a number of localities and particularly around the Isle of Man. Often the valves are heavily encrusted with various organisms particularly sponges. This relationship has been described as protective-mutualism. The sponge is thought to protect the scallop from predation by starfishes while the sponges are protected from predation by the sea slug, Archidoris pseudoargus. Scallops detach from their byssal thread at some point in their life, usually upon attaining 1.5-2.0 cm but retains the ability to secrete a byssus until at least 6.5 cm long.

Listed by

- none -

Further information sources

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  1. Christensen, J.M., 1980. Seashells. Bivalves of the British and Northern European Seas. Revised and adapted by Peter S. Dance. Hamondsworth: Penguin Books Ltd.

  2. Fish, J.D. & Fish, S., 1996. A student's guide to the seashore. Cambridge: Cambridge University Press.

  3. Hayward, P.J. & Ryland, J.S. (ed.) 1995b. Handbook of the marine fauna of North-West Europe. Oxford: Oxford University Press.

  4. 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.]

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

  6. Seaward, D.R., 1982. Sea area atlas of the marine molluscs of Britain and Ireland. Peterborough: Nature Conservancy Council.

  7. 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:

Carter, M.C. 2008. Aequipecten opercularis Queen 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 19-09-2018]. Available from:

Last Updated: 29/05/2008