Description: A brittle shell with a broadly triangular outline, reaching a maximum of 4 cm in length. In older specimens the shell is yellow with red rays or zigzag markings, but in younger specimens the shell may be almost completely red with little yellow colouration visible. The outer surface may also be covered in part by the yellow-brown periostracum. The inside of the shell is pearly white and the muscle scars are not easily visible. The external rays are visible on the inside of the shell.

Habitat: Usually offshore down to around 80 m, but have been recorded from scattered localities around the coasts.

Distribution: Rarely recorded, most records are from south to southwest Britain. Some records from west coast of Ireland and Northern Ireland.

Similar Species: Could be easily confused with juvenile Modiolus modiolus.

Key Identification Features:

• Yellow shell with red rays or zigzags.
• Juveniles/younger specimens may be almost completely red.
• Pearly white interior with no easily visible muscle scars
• External rays visible on interior.

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

iNaturalist: Modiolus adriaticus at iNaturalist World Species Observations database.

GBIF data for Modiolus adriaticus

WoRMS: Modiolus adriaticus at World Register of Marine Species. Accepted name: Modiolus adriaticus Lamarck, 1819. AphiaID: 140462.

Classification: Biota; Animalia; Mollusca; Bivalvia; Autobranchia; Pteriomorphia; Mytilida; Mytiloidea; Modiolidae; Modiolinae; Modiolus