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Syrinx aruanus, common name the Australian trumpet or false trumpet, is a species of extremely large sea snail measuring up to 75 cm long and weighing up to 18 kg. It is a marine gastropod mollusk in the family Turbinellidae, and is the only species in the genus Syrinx.
Gastropods have the greatest numbers of named mollusk species. However, estimates of the total number of gastropod species vary widely, depending on cited sources. 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]
Some evolutionary lineages of gastropods have evolved a proboscis. In gastropods, the proboscis is an elongation of the snout with the ability to retract inside the body; it can be used for feeding, sensing the environment, and in some cases, capturing prey or attaching to hosts.
In many marine gastropods where the siphon is particularly long, the structure of the shell has been modified in order to house and protect the soft tissue of the siphon. This shell modification is known as the siphonal canal. For a gastropod whose shell has an exceptionally long siphonal canal, see Venus comb murex.
Opisthobranchia represents a morphologically diverse group of gastropods occupying a great variety of ecological niches. Opisthobranchs have a global distribution, but are restricted almost exclusively to marine habitats with the only exception being few freshwater acochlidians .
The molluscan shell has been internalized in a number of lineages, including the coleoid cephalopods and many gastropod lineages. Detorsion of gastropods results in an internal shell, and can be triggered by relatively minor developmental modifications such as those induced by exposure to high platinum concentrations. [41]
Gastropods that have limpet-like or patelliform shells are found in several different clades: Clade Patellogastropoda, example Patellidae, the true limpets, all marine, in five living families and two fossil families; Clade Vetigastropoda, examples Fissurellidae, (the keyhole limpets and slit limpets), and Lepetelloidea, small deepwater limpets
In some gastropods, the aperture is narrowed by protruding plaits, which help make the soft parts of the animal less vulnerable to predation. The growth of the shell is provided for by non-continuous addition of minute layers to the aperture margin (also called peristome) from the mantle border, the principal agent in the secretion of the shell.