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Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks[a] (/ ˈmɒləsks /). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. [4] The number of additional fossil species is estimated between 60,000 and 100,000, [5] and the ...
Gastropods (/ ˈɡæstrəpɒdz /), commonly known as slugs and snails, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (/ ɡæsˈtrɒpədə /). [5] This class comprises snails and slugs from saltwater, freshwater, and from the land. There are many thousands of species of sea snails and slugs, as ...
Biomineralization. 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.
An octopus (pl.: octopuses or octopodes[a]) is a soft-bodied, eight-limbed mollusc of the order Octopoda (/ ɒkˈtɒpədə /, ok-TOP-ə-də[3]). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like other cephalopods, an octopus is bilaterally symmetric with two eyes and ...
Terrestrial mollusc. Land snail Helix pomatia. Land slug Bielzia coerulans. Terrestrial molluscs or land molluscs (mollusks) are an ecological group that includes all molluscs that live on land in contrast to freshwater and marine molluscs. They probably first occurred in the Carboniferous, arising from freshwater ones.
Both octopuses and squids have mantles (referenced above) which function towards respiration and locomotion in the form of jetting. The composition of these mantles differs between the two families, however. In octopuses, the mantle is made up of three muscle types: longitudinal, radial, and circular.
The evolution of the molluscs is the way in which the Mollusca, one of the largest groups of invertebrate animals, evolved. This phylum includes gastropods, bivalves, scaphopods, cephalopods, and several other groups. The fossil record of mollusks is relatively complete, and they are well represented in most fossil-bearing marine strata.
Bivalvia. Bivalvia (/ baɪˈvælviə /) 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.