Bivalves move primarily using a specialized muscular foot. This foot is pointed and retractable, allowing the bivalve to extend it into the surrounding sediment (such as sand or mud) and then pull itself forward or dig deeper. The movement involves the following steps:
- The bivalve relaxes its adductor muscles to open its shell slightly.
- It extends its foot downward into the substrate.
- The tip of the foot dilates to anchor in the sediment.
- The adductor muscles contract to close the shell and retract the foot, pulling the bivalve downward or forward.
- This process is repeated to enable burrowing or locomotion through the sediment.
Additionally, some bivalves like scallops can swim short distances by rapidly opening and closing their shells using their adductor muscles, ejecting water to propel themselves
. In summary, bivalves move by using their muscular foot to dig and pull themselves through sediment, and some species can swim by valve clapping.
