Bivalvia
Bivalvia
Bivalvia (pronounced: bih-VAL-vee-uh), also known as bivalves, is a class of marine and freshwater mollusks that includes clams, oysters, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater.
Etymology
The name "Bivalvia" comes from the Latin bis, meaning "two", and valvae, meaning "leaves of a door". This refers to the two shells, or valves, that make up the protective covering of the animal.
Anatomy
Bivalves have a hard calcium carbonate shell made of two parts or "valves". The two valves are connected by a hinge. Most bivalves have two identical shells, which are mirror images of each other. The animal's body lies within the shell, which provides protection from predators and environmental conditions.
Habitat and Distribution
Bivalves are found in all types of aquatic habitats, both marine and freshwater. They are particularly common in the oceans, where they often form large colonies on the seafloor. Some species of bivalves, such as the Zebra mussel, have become invasive in certain parts of the world, causing significant ecological and economic damage.
Reproduction
Most bivalves are dioecious, meaning they have separate male and female individuals. Fertilization usually takes place externally in the water column. The resulting larvae, known as veligers, are planktonic and drift with the currents until they find a suitable substrate to attach to and metamorphose into juvenile bivalves.
Related Terms
- Mollusca: The phylum to which bivalves belong.
- Gastropoda: Another class of mollusks, which includes snails and slugs.
- Cephalopoda: Another class of mollusks, which includes octopuses, squids, and cuttlefish.
External links
- Medical encyclopedia article on Bivalvia
- Wikipedia's article - Bivalvia
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