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Bivalvia (/ b aɪ ˈ v æ l v i ə /) or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consisting of a hinged pair of half-shells known as valves.
Freshwater bivalves are molluscs of the order Bivalvia that inhabit freshwater ecosystems. They are one of the two main groups of freshwater molluscs , along with freshwater snails . The majority of bivalve molluscs are saltwater species that live in the marine habitats , but a number of families have evolved to live in fresh water (and in some ...
Velesunio wilsonii come from one of two classes of molluscs that have successfully inhabited freshwater ecosystems. [1] All other mollusc classes remain in marine ecosystems . [ 1 ] Bivalve molluscs evolved in marine ecosystems before slowly moving into estuaries and inhabiting upstream freshwater habitats, evolving to tolerate lower salinity ...
The two major classes of molluscs have representatives in freshwater: the gastropods (snails) and the bivalves (freshwater mussels and clams.) It appears that the other classes within the Phylum Mollusca -the cephalopods, scaphopods, polyplacophorans, etc. - never made the transition from a fully marine environment to a freshwater environment.
An assortment of shells of marine bivalves and a few marine gastropods found on a beach in Wales In May 2010, a new taxonomy of the Bivalvia was published in the journal Malacologia . The 2010 taxonomy is known as the Taxonomy of the Bivalvia (Bouchet, Rocroi, Bieler, Carter & Coan, 2010) [ citation needed ] .
As Joseph Rosewater [1] commented in 1961: "“The Pinnidae have considerable economic importance in many parts of the world. They produce pearls of moderate value. In the Mediterranean area, material made from the holdfast or byssus of Pinna nobilis Linné has been utilized in the manufacture of clothing for many centuries: gloves, shawls, stockings and cloaks.
A marine coastal ecosystem is a marine ecosystem which occurs where the land meets the ocean. Worldwide there is about 620,000 kilometres (390,000 mi) of coastline. Coastal habitats extend to the margins of the continental shelves, occupying about 7 percent of the ocean surface area.
In modern environments, seagrass, lucinid bivalves, and the sulfur-oxidizing symbionts constitute a three-way symbiosis. Because of the lack of oxygen in coastal marine sediments, dense seagrass meadows produce sulfide-rich sediments by trapping organic matter that is later decomposed by sulfate-reducing bacteria. [ 12 ]