: Consists of two symmetrical valves connected by a flexible ligament and a "lock" (hinge).
: The body is laterally compressed and divided into two main parts: the trunk and the wedge-shaped foot . Unlike gastropods, bivalves lack a head, tentacles, and eyes. gdz biologiia 7 sumatokhin klass dvukhstvorchatye molliuski
: Some species (pearl oysters) produce pearls and mother-of-pearl (nacre) used in jewelry. : Consists of two symmetrical valves connected by
: As filter feeders, they clean bodies of water by removing organic suspension. : Some species (pearl oysters) produce pearls and
: They are filter feeders . Water enters through an inhalant siphon, passes over the gills where food particles are trapped, and exits through an exhalant siphon.
: Like most mollusks, they have an open circulatory system where the heart pumps blood into the body cavity. Internal Anatomy Summary Characteristic Digestive
(class Bivalvia ) are a unique group of aquatic mollusks characterized by a shell consisting of two hinged valves and, most notably, the absence of a head . In the Grade 7 Biology curriculum by Sumatohin, they are studied as essential bio-filters and members of aquatic ecosystems. Key Biological Features