Tellin Shell (Tellina tenuis)

Tellin shell burrowing (note the muscular foot)

This delicate and beautiful bivalve has a pair of flat pink or white shells which have a glossy sheen. About 2 cm across. When the empty shells lie on the sand they look like butterflies.

This bivalve has a large muscular foot for rapid burrowing as the tide goes out. It can change the shape of the foot with blood pressure to pierce the sand and contract to pull the mollusc down into the substrate. When burrowed in the sand two, quite separate, long siphons allow contact with the surface. It feeds on organic debris which settles out on the sand surface. One siphon enables it to draw in food, like a vacuum cleaner, and oxygenated water whilst the other moves water in the other direction getting rid of waste. Gills filter the detritus which is passed to the mouth for consumption. The density of tellins is high in an area of clean sand and surface contact with the siphons may be the way in which they can space themselves out to prevent intraspecific competition. They are common in clean sand and found on depositing beaches around the north Atlantic and down the Channel.

The separate siphons of a tellin partly burrowed.

See the Sand Gaper