Neogastropoda

From Wikipedia, the free encyclopedia

Neogastropoda

Scientific classification

Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Orthogastropoda
Superorder:	Caenogastropoda
Order:	Sorbeoconcha
Suborder:	Hypsogastropoda
Infraorder:	Neogastropoda

Superfamilies

Buccinoidea
Cancellarioidea
Conoidea
Muricoidea
Volutoidea

The Neogastropoda used to be an order of prosobranch gastropods in the taxonomy of Thiele (1921). They are now included in the infraorder Neoogastropoda Cox, 1960. A more detailed account about the discussion on the taxonomy of the Gastropoda is given in Gastropoda, Archaeogastropoda and Mesogastropoda.

[edit] Description

The Neogastropoda are the modern marine snails. They evolved in a much later stage than the Archaegastropoda and the Mesogastropoda. The first specimens of these prosobranchs 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.

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, have only three denticles (small teeth) in each transverse row.

The Neogastropoda have separate sexes.

There are about 16,000 species. Neogastropoda includes many well-known gastropods such as the cone snails, conchs, mud snails, olive snails, oyster drills, tulip snails, and whelks. The Neogastropoda all live in the sea, except Clea, a rare freshwater genus. They are mostly predators, some are saprophagous (scavengers).