Gdz Biologiia 7 Sumatokhin Klass Dvukhstvorchatye Molliuski Onlain Official

: They possess an open circulatory system with a heart and vessels.

: The nervous system is simplified, consisting of three pairs of ganglia. Ecological and Economic Importance : They possess an open circulatory system with

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

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

For further study and visual aids, students can refer to educational platforms like Yaklass or watch lesson summaries on YouTube .

: Students typically study the Anodonta (swan mussel), Unio (painter's mussel), and marine species like the edible mussel and giant clam.