Description: This bivalve is a common sight around most shores, with a distinctive oval to subtriangluar shell, reaching up to 10 cm, but more often around 6 cm. The umbones are rounded and not downturned. It can range from purple, blue to light brown or olive coloured. It is usually a lighter horn to brown colour when younger and dark purplish-blue when older. Periostracum can be deep blue, black or dirty brown and can give the shells a very dark appearance. Fine concentric growth rings are visible. Mantle edge light yellow-brown.

Habitat: Attached to hard substrata from rocky shores to artificial structures in harbours and marinas. Found from upper intertidal to shallow sublittoral.

Distribution: Widespread around all coasts of Britain and Ireland.

Similar Species: Could be confused with other species of Mytilus especially Mytilus galloprovincialis, and it is known that hybridisation between species occurs.

Key Identification Features:

• Distincitve and well known shell.
• Purple, blue or horn coloured shell with dark periostracum.
• Mantle edge light yellow-brown.
• Rounded umbones.

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

iNaturalist: Mytilus edulis at iNaturalist World Species Observations database.

GBIF data for Mytilus edulis

WoRMS: Mytilus edulis at World Register of Marine Species. Accepted name: Mytilus edulis Linnaeus, 1758. AphiaID: 140480.

Classification: Biota; Animalia; Mollusca; Bivalvia; Autobranchia; Pteriomorphia; Mytilida; Mytiloidea; Mytilidae; Mytilinae; Mytilus