Description: A solid shell with a broadly oval to triangular outline. It can reach up to 11.5 cm in length but is more commonly smaller. It is usually cream in colour with pale brown rays. It may be partially covered by the yellow to green periostracum, which tends to be more prominent at the margin. Growth stages are clearly visible and there are fine concentric lines on the outer surface of the shell. Right valve has 2 short cardinal teeth, left valve has 3. Right valve with 2 anterior and 2 posterior laterals, left valve with 1 anterior and 1 posterior lateral tooth. Inside of shell is white with hints of pale brown, but may have some hint of the exterior colour visible. Pallial sinus wide and shallow.

Habitat: Clean sand, from intertidal down to around 50 m depth.

Distribution: No records from the island of Ireland to date. Few records from Britain but these are mostly confined to southern or south western areas with a few other scattered records which may need to be verified.

Similar Species: A lot of superficially similar bivalves do not reach the larger size of this species but smaller specimens may be confused with some of these species.

Key Identification Features:

• Oval to triangular outline.
• 2 short cardinal teeth in right valve.
• 3 cardinal teeth in left valve.
• Pallial line wide and shallow.

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

iNaturalist: Mactra glauca at iNaturalist World Species Observations database.

GBIF data for Mactra glauca

WoRMS: Mactra glauca at World Register of Marine Species. Accepted name: Mactra glauca Born, 1778. AphiaID: 140297.

Classification: Biota; Animalia; Mollusca; Bivalvia; Autobranchia; Heteroconchia; Euheterodonta; Imparidentia; Venerida; Mactroidea; Mactridae; Mactrinae; Mactra