Gdz Biologiia 7 Sumatokhin Klass Dvukhstvorchatye Molliuski Onlain [Complete]

: Unlike gastropods (snails), bivalves lack a distinct head. Their body consists of a torso and a muscular "foot" used for burrowing or anchoring.

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 : Unlike gastropods (snails), bivalves lack a distinct head

: Many species, such as scallops and oysters, are significant food sources for humans. Freshwater pearl mussels are also cultivated for pearl production. In the 7th-grade biology curriculum by S

: Most bivalves are filter feeders. They draw water into their mantle cavity through a siphon, where specialized gills trap organic particles. Internal Systems Key Biological Features : Many species, such as

: 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).

: They breathe through plate-like gills (ctenidia) located in the mantle cavity.