Gdz Biologiia 7 Sumatokhin Klass Dvukhstvorchatye Molliuski Onlain Guide

: Most bivalves are filter feeders. They draw water into their mantle cavity through a siphon, where specialized gills trap organic particles. Internal Systems

: 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). : Most bivalves are filter feeders

: The nervous system is simplified, consisting of three pairs of ganglia. Ecological and Economic Importance a middle calcareous layer

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

: Many species, such as scallops and oysters, are significant food sources for humans. Freshwater pearl mussels are also cultivated for pearl production.