: The nervous system is simplified, consisting of three pairs of ganglia. Ecological and Economic Importance
: They breathe through plate-like gills (ctenidia) located in the mantle cavity.
: Most bivalves are filter feeders. They draw water into their mantle cavity through a siphon, where specialized gills trap organic particles. Internal Systems : The nervous system is simplified, consisting of
: Many species, such as scallops and oysters, are significant food sources for humans. Freshwater pearl mussels are also cultivated for pearl production.
: By filtering vast amounts of water, bivalves like mussels and oysters act as natural water purifiers in ecosystems. They draw water into their mantle cavity through
: The body is laterally compressed and enclosed in a bilateral shell. This shell consists of three layers: an outer organic layer (periostracum), a middle calcareous layer, and an inner pearly layer (nacre).
: Unlike gastropods (snails), bivalves lack a distinct head. Their body consists of a torso and a muscular "foot" used for burrowing or anchoring. : By filtering vast amounts of water, bivalves
The Class Bivalvia (Двустворчатые моллюски) is a group of aquatic mollusks characterized by a shell composed of two hinged parts. In the 7th-grade biology curriculum by S.V. Sumatokhin and V.V. Pasechnik, these organisms are studied for their unique evolutionary adaptations to a sedentary lifestyle. Key Biological Features