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Molluscs have developed such a varied range of body structures, finding synapomorphies (defining characteristics) to apply to all modern groups is difficult. [15] The most general characteristic of molluscs is they are unsegmented and bilaterally symmetrical. [16] The following are present in all modern molluscs: [17] [19]
The number of gastropod species can be ascertained from estimates of the number of described species of Mollusca with accepted names: about 85,000 (minimum 50,000, maximum 120,000). [9] But an estimate of the total number of Mollusca, including undescribed species, is about 240,000 species. [10]
The mouth is located within the animal's undeveloped head in front of its single large foot and contains a radula, a defining characteristic of the mollusca. Tentacles are situated behind the mouth. They also have a cone-shaped stomach with a single crystalline style though no gastric shield. The intestines are long and make between four and ...
Nautilus (from Latin nautilus 'paper nautilus', from Ancient Greek ναυτίλος nautílos 'little sailor') [3] are the ancient pelagic marine mollusc species of the cephalopod family Nautilidae.
List of mollusc orders illustrates the 97 orders in the phylum Mollusca, the largest marine animal phylum. 85,000 extant species are described, [1] making up 23% of described marine organisms. [ 2 ] Class Aplacophora
A clam shell (species Spisula solidissima) at Sandy Hook, New Jersey. Clam is a common name for several kinds of bivalve mollusc.The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the sea floor or riverbeds.
Conchifera is a subphylum of the phylum Mollusca, containing five extant classes: Monoplacophora, Cephalopoda, Gastropoda, Bivalvia, and Scaphopoda. [1] Conchiferans can bear a single shell as in snails and ammonites, a single pair of shells as in clams, or lack a shell as in slugs and squid.
The taxonomic term Bivalvia was first used by Linnaeus in the 10th edition of his Systema Naturae in 1758 to refer to animals having shells composed of two valves. [3] More recently, the class was known as Pelecypoda, meaning "axe-foot" (based on the shape of the foot of the animal when extended).