Bivalve
Bivalve
Bivalve (/ˈbaɪvælv/), from the Latin bis (meaning "two") and valvae (meaning "leaves of a door"), is a type of mollusk that is characterized by a shell that is divided into two hinged parts or valves.
Anatomy
The body of a bivalve is protected by a calcium carbonate shell composed of two asymmetrical parts, typically of equal size. These two parts are attached by a flexible hinge. The shell is opened and closed by the contraction and relaxation of two adductor muscles, which are located on the anterior and posterior sides of the body.
Classification
Bivalves are part of the phylum Mollusca, which also includes other classes such as Gastropoda (snails and slugs), Cephalopoda (squids and octopuses), and Scaphopoda (tusk shells). The class Bivalvia is further divided into several orders, including Veneroida, Mytiloida, and Pterioida, among others.
Habitat and Distribution
Bivalves are found in a wide range of habitats, from freshwater environments such as rivers and lakes, to marine environments including coastal areas and the deep sea. They are distributed globally, from the tropics to the poles.
Diet and Feeding
Most bivalves are filter feeders, extracting organic particles from water by pumping it through their gills. Some species, however, are deposit feeders, ingesting sediment and extracting organic material from it.
Reproduction
Bivalves typically reproduce by releasing eggs and sperm into the water, where fertilization occurs. Some species, however, retain the eggs inside their bodies and give birth to live young.
Economic Importance
Many bivalve species are economically important as food sources for humans. These include oysters, clams, mussels, and scallops. Some species are also harvested for their pearls.
See Also
- Mollusca
- Gastropoda
- Cephalopoda
- Scaphopoda
- Veneroida
- Mytiloida
- Pterioida
- Filter feeder
- Deposit feeder
External links
- Medical encyclopedia article on Bivalve
- Wikipedia's article - Bivalve
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