Description: This small scallop grows to around 6 cm in length and is very variable in colour, often with irregular patterning. Both valves are convex, with 25-35 uniform ridges with spines, and oval shaped, aside from the protruding auricles (ears) at the hinge. Growth rings are often visible on the shell. The inner surface of the shell is glossy and has similar colouration to the outside of the shell. The ears are unequal in size, with the anterior 2-3 times larger than the posterior, they are so unequally sized that people often assume one has been broken off. There is a prominent byssal notch and fine teeth on lower edge of the right anterior ear (larger ear on right hand shell).

Habitat: Rocky substrata, occasionally algal holdfasts. Can be free-living (older specimens) or attached by byssus threads. Found from lower shore to depths of 100 m.

Distribution: Found all around Britain and Ireland where there is suitable substrate.

Similar Species: Most likely to be confused with Talochlamys pusio, but these have more ribs on their shell (35 - 70 ribs in T. pusio, 25-35 in M. varia) and the ribs on M. varia are equal in width, whereas in T. pusio they alternate between thick and thin. Could potentially be confused with the queen scallop Aequipecten opercularis, or juvenile king scallop Pecten maximus but these species do not have unequal ears.

Key Identification Features:

• Unequal ears; anterior 2-3 times larger than posterior.
• 25-35 uniform ridges on shell.
• Prominent byssal notch on right anterior (larger) ear.
• Fine teeth on lower edge of right anterior ear.

Distribution Map from NBN: Mimachlamys varia at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Mimachlamys varia at iNaturalist World Species Observations database.

GBIF data for Mimachlamys varia

WoRMS: Mimachlamys varia at World Register of Marine Species. Accepted name: Mimachlamys varia (Linnaeus, 1758). AphiaID: 236719.

Classification: Biota; Animalia; Mollusca; Bivalvia; Autobranchia; Pteriomorphia; Pectinida; Pectinoidea; Pectinidae; Pedinae; Mimachlamydini; Mimachlamys