Final answer:
Bivalves are filter-feeders that use their gills to capture food from water. They lack a radula and have a flattened body with a muscular foot.
Step-by-step explanation:
Bivalves, such as clams and mussels, filter-feed to extract oxygen and capture food from water. They have a pair of large gills that allow water to enter their bodies. The food particles are trapped by mucus on the gills and transferred to the mouth by cilia. Bivalves lack a radula and have a flattened body with a muscular foot that can be used for anchoring or burrowing.