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The four most universal features defining modern molluscs are a soft body composed almost entirely of muscle, a mantle with a significant cavity used for breathing and excretion, the presence of a radula (except for bivalves), and the structure of the nervous system. Other than these common elements, molluscs express great morphological ...
Bivalve molluscs (e.g. clams and oysters) have a shell which is composed of two separate but articulating parts. Each one of these two parts is known as a "valve". The two valves are known as the "right valve" and the "left valve"; these are labeled with respect to the anterior end of the bivalve, when the umbones are facing upward.
The mollusc (or mollusk [spelling 1]) shell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, which includes snails, clams, tusk shells, and several other classes. Not all shelled molluscs live in the sea; many live on the land and in freshwater.
The gastropod shell is part of the body of many gastropods, including snails, a kind of mollusc. The shell is an exoskeleton , which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium storage.
In species where the shell is small compared to the size of the body, more of the mantle shows. Shell-less slugs have the mantle fully visible. The dorsal surface of the mantle is called the notum, while the ventral surface of the mantle is called the hyponotum. In the family Philomycidae, the mantle covers the whole back side of the body. [2]
The age of bivalve molluscs can be estimated in several ways. The Noah's Ark clam Arca noae has been used to compare these methods: the annual growth rings on the exterior of the valves can be counted at one per year and give a satisfactory result, but sometimes spurts of growth occur which may create an extra ring and cause confusion. Early ...
Pages in category "Mollusc anatomy" The following 35 pages are in this category, out of 35 total. This list may not reflect recent changes. A. Aesthete (chiton)
The internal anatomy is visible, including the paired siphons to the right. A siphon is an anatomical structure which is part of the body of aquatic molluscs in three classes: Gastropoda, Bivalvia and Cephalopoda (members of these classes include saltwater and freshwater snails, clams, octopus, squid and relatives).