Scallops like Pecten maximus and Chlamys spp. are among the most familiar of the bivalves that live unattached on the seabed. They lie in their flattened sides and make depressions in the sand in which to settle by expelling jets of water from their mantle cavities. These bivalves can swim and escape from starfish, their worse enemies, by clapping their valves together.
Tail piece from Edward Forbes’ book ‘The British Starfish’ (1841).