Bivalves

Bivalves are a class of marine and freshwater molluscs with bodies enclosed by a shell consisting of two hinged parts. Bivalves include clams, oysters, mussels, scallops, and other shellfish. They are an important group within the phylum Mollusca, which also includes snails, squids, and octopuses.

Anatomy and Physiology

Bivalves have a laterally compressed body enclosed by a shell made of calcium carbonate. The shell is typically composed of two parts, or valves, connected by a flexible ligament. The anatomy of bivalves includes a muscular foot used for movement and digging, gills for breathing and feeding, and a mantle which secretes the shell material.

Ecology and Habitat

Bivalves inhabit a wide range of environments from freshwater to marine ecosystems. They are found buried in sand or mud, attached to rocks or other surfaces, or free-living. Bivalves play a crucial role in the aquatic ecosystem as filter feeders; they help maintain water clarity and quality by filtering out plankton and organic particles.

Reproduction

Bivalves reproduce sexually by releasing sperm and eggs into the water. In some species, there is a larval stage called a "veliger" that is planktonic before settling down and metamorphosing into the adult form.

Economic Importance

Many bivalves are economically important as food sources for humans. Species such as oysters, clams, and mussels are cultivated for aquaculture, while others are harvested from wild populations. Bivalves are also used in pearl production, particularly the pearl oysters in the genus Pinctada.

Conservation

Bivalve populations are threatened by overfishing, habitat loss, and pollution. Conservation efforts are crucial to maintain sustainable populations, especially in areas heavily impacted by human activities.

See Also

• Mollusca
• Aquaculture
• Marine biology