Biodiversity & Conservation

Queen scallop - Aequipecten opercularis

Aequipecten opercularis

Image Keith Hiscock - Aequipecten opercularis on mixed substrata. Image width ca 15 cm.
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Distribution map

Aequipecten opercularis recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

Why do the maps differ?

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Aequipecten opercularis is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Mollusca Snails, slugs, mussels, cockles, clams & squid
Class Bivalvia Clams, cockles, mussels, oysters, and scallops
Authority Linnaeus, 1758
Recent synonyms Chlamys opercularis
Map icon Recorded Distribution in Britain and Ireland Found around all British and Irish coasts.
Habitat information icon Habitat information 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.
Text page icon Description 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.
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 icon 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.

This review can be cited as follows:

Michelle Carter 2009. Aequipecten opercularis. Queen scallop. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 04/02/2012]. Available from: <http://www.marlin.ac.uk/speciesinformation.php?speciesID=2390>