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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.
The estimate of 85,000 mollusks includes 24,000 described species of terrestrial gastropods. [9] Different estimates for aquatic gastropods (based on different sources) give about 30,000 species of marine gastropods, and about 5,000 species of freshwater and brackish gastropods. Many deep-sea species remain to be discovered, as only 0.0001% of ...
The name chiton is Neo-Latin derived from the Ancient Greek word khitōn, meaning tunic (which also is the source of the word chitin). The Ancient Greek word khitōn can be traced to the Central Semitic word *kittan, which is from the Akkadian words kitû or kita'um, meaning flax or linen, and originally the Sumerian word gada or gida ...
The mantle cavity is a central feature of molluscan biology. This cavity is formed by the mantle skirt, a double fold of mantle which encloses a water space. This space contains the mollusk's gills, anus, osphradium, nephridiopores, and gonopores. The mantle cavity functions as a respiratory chamber in most mollusks. In bivalves it is usually ...
Siphons in molluscs are tube-like structures in which water (or, more rarely, air) flows. The water flow is used for one or more purposes such as locomotion, feeding, respiration, and reproduction. The siphon is part of the mantle of the mollusc, and the water flow is directed to (or from) the mantle cavity. A single siphon occurs in some ...
Scaphopoda / s k æ ˈ f ɒ p ə d ə / (plural scaphopods / ˈ s k æ f ə p ɒ d z /, from Ancient Greek σκᾰ́φης skáphē "boat" and πούς poús "foot"), whose members are also known as tusk shells or tooth shells, are a class of shelled marine invertebrates belonging to the phylum Mollusca with worldwide distribution and are the only class of exclusively infaunal marine molluscs.
Bivalve molluscs are used as bioindicators to monitor the health of aquatic environments in both fresh water and the marine environments. Their population status and structure, physiology, behaviour and their levels of contamination with chemicals together provide a detailed indication of the status of the ecosystem.
Variety of Mollusc shells (gastropods: land snail shells and seashells). Closed and open shells of a marine bivalve, Petricola pholadiformis. A bivalve shell is composed of two hinged valves which are joined by a ligament. Four views of a shell of the land snail Arianta arbustorum The giant clam (Tridacna gigas) is the largest extant species of ...