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The Neogastropoda was, for many years, an order of sea snails, marine gastropod mollusks. In the current version of gastropod taxonomy however, Neogastropoda is an unranked clade of sea snails. When Neogastropoda was an order, it was placed within the prosobranch gastropods according to the taxonomy developed by Thiele (1921). The families which used to form the order Neogastropoda are now included in the clade Neogastropoda Cox, 1960. A more detailed account of the current taxonomy of the gastropods is laid out in the article Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005).[1]
[edit] DescriptionThe Neogastropoda are a fairly recent group of marine snails. The first specimens are found in layers of the Late Cretaceous, about 70 million years ago. They only have one auricle, one kidney and one monopectinate gill, i.e. the gill filaments develop on only one side of the central axis.[2] The shell has a well-developed siphonal canal. The elongated trunk-like siphon is an extensible tube, formed from a fold in the mantle. It is used to suck water into the mantle cavity. At the base of the siphon is the bipectinate (branching from a central axis) osphradium, a sensory receptacle and olfactory organ, that is more developed than the one in the Mesogastropoda. The nervous system is very concentrated. Many species have the ganglia in a compact space. The rachiglossate (rasp-like) radula, a layer of serially arranged teeth within the mouth, has only three denticles (small teeth) in each transverse row.[2] The Neogastropoda have separate sexes. There are about 16,000 species. Neogastropoda includes many well-known gastropods including the cone snails, conchs, mud snails, olive snails, oyster drills, tulip shells, and whelks. The Neogastropoda all live in the sea, except Clea, a rare freshwater genus. They are mostly predators, but some are saprophagous (scavengers). [edit] Superfamilies
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