Final answer:
Bivalves use their gills and the action of cilia to pump water through their bodies, allowing for both respiration and feeding.
Step-by-step explanation:
The process used to pump water through bivalves involves a specialized structure called the gill, which functions in both respiration and feeding. Bivalves, such as clams, mussels, and oysters, draw water in through an opening called the inhalant siphon, pass it over their gills where gas exchange and feeding occur, and then expel it through the exhalant siphon.
The movement of water is facilitated by the action of cilia, which are tiny hair-like structures that cover the gills and beat in a coordinated fashion to create a steady flow of water.