Gdz Biologiia 7 Sumatokhin Klass Dvukhstvorchatye Molliuski May 2026

: 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 gdz biologiia 7 sumatokhin klass dvukhstvorchatye molliuski

: Some species (pearl oysters) produce pearls and mother-of-pearl (nacre) used in jewelry. : Like most mollusks, they have an open

Mouth (near the foot), stomach, liver, and intestine. They lack a radula (grating tongue). Plate-like gills (ctenidia) located in the mantle cavity. Excretory Two kidneys that open into the mantle cavity. Nervous Simplified, consisting of three pairs of ganglia. Ecological and Economic Importance Key Biological Features : Some species (pearl oysters)