Description: The fan mussel is considered to be one of the most endangered molluscs in UK waters. It is the largest bivalve found in Britain and Ireland growing to around 30 cm in length (can be up to 48 cm) by about 15 cm at the widest point, narrowing towards the base giving it a fan-like shape. The shell is very thin and fragile and has a number of concentric lines as well as 10-12 ribs, which can have fluted spines. It is light yellow to dark brown in colour. The shell margin is usually smooth, but can be fragmented at the exposed end as it is so fragile.

Habitat: Usually almost completely buried in soft mud or sand.

Distribution: Very rare; records from Scotland, north of Ireland and SW England and Wales. Has been heavily impacted by bottom fishing.

Similar Species: Unlikely to be confused with any other species.

Key Identification Features:

• Large fan-shaped bivalve, reaching 30-48 cm.
• Very thin, fragile shell with concentric lines and 10-12 ribs.
• Light yellow to dark brown in colour.
• Usually buried in sediment.

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

iNaturalist: Atrina fragilis at iNaturalist World Species Observations database.

GBIF data for Atrina fragilis

WoRMS: Atrina fragilis at World Register of Marine Species. Accepted name: Atrina fragilis (Pennant, 1777). AphiaID: 146524.

Classification: Biota; Animalia; Mollusca; Bivalvia; Autobranchia; Pteriomorphia; Ostreida; Pinnoidea; Pinnidae; Atrina