coup de grÃ¢ce in British English. See all translations. coup de grÃ¢cenoun [ S ] uk â /ËkuË dÉ ËÉ¡rÉËs/ us â /ËkuË dÉ ËÉ¡rÉËs/ formal. âº an action that ends something that has been gradually getting worse, or that kills a person or animal in order to end their suffering: Jane's affair was the coup de grÃ¢ce to her disintegrating marriage. Thesaurus: synonyms and related words.
Bivalves is a class of marine and freshwater molluscs with about 30,000 species including scallops, clams, oysters, razor shells, shipworms and mussels. Most bivalves are marine usually found in shallower water but some live in brackish and freshwater.
Bivalves are exclusively aquatic; they include both marine and freshwater forms. However some, for instance the mussels, can survive out of water for short periods by closing their valves. Bivalves are unique among the mollusks for lacking a radula; they feed by siphoning and filtering large particles from water. Some bivalves are epifaunal: that is, they attach themselves to surfaces in the water, by means of a byssus or organic cementation. Others are infaunal: they bury themselves in sand or other sediments.