How are bivalves different from snails and slugs?

Bivalves differ from snails and slugs (which are members of the class Gastropoda) in several fundamental ways related to their anatomy and feeding habits:

• Shell Structure: Bivalves are characterized by a shell divided into two distinct parts, known as left and right valves, which are connected by a hinge. In contrast, snails typically possess a single, often coiled shell, while slugs have a shell that is either greatly reduced, internal, or entirely absent.123
• Head and Sensory Organs: Unlike most mollusks, including snails, bivalves have lost their head and associated sensory organs.1
• Feeding Mechanisms: Snails and slugs utilize a radula—a ribbonlike, tooth-covered structure used for rasping or drilling food—to feed. Bivalves lack a radula entirely. Instead, most bivalves are ciliary suspension feeders that use modified respiratory gills, called ctenidia, to filter food particles from the water.2415
• Lifestyle: While gastropods exhibit immense ecological diversity and occupy nearly all habitats, bivalves are generally sedentary, often burrowing into sediments or attaching themselves to hard surfaces using byssal threads.15