Mya truncata

Linné, 1758

Description (shell):
Shell thick and strong, quadrate, umbones on midline; anterior end regularly rounded, posterior abruptly truncate. Sculpture of coarse concentric grooves, growth stages clear. Left valve with a prominent spatulate chondrophore, projecting at a right angle to hinge, bounded anteriorly and posteriorly by a distinct ridge. Right valve with a concave, spatulate chondrophore recessed beneath umbo, a blunt ridge bounding it anteriorly. Pallial line and adductor scars distinct, anterior scar elongate, posterior rounded (M. truncata-drawing).

Up to 70 mm long.

Dull white to light brown, periostracum light olive to brown. Inner surfaces white.

The siphons are connected throughout their length and though they may be completely withdrawn into the shell, they are usually fully extended. This has caused the hinder end of the shell to gape widely. These animals are deep burrowers and the foot is positioned downwards, while the siphons reach straight up through sand or mud to the water above (M. truncata).

In mixed sandy substrata, from the lower shore to about 70 m.

Circumboreal, in the north-east Atlantic extending south to Biscay (Distr. M. truncata).