Odostomiinae


Odostomiinae, Odostomia snails and their allies, is a taxonomic subfamily of minute parasitic sea snails. These are marine heterobranch gastropod mollusks, or micromollusks, in the family Pyramidellidae.

Taxonomy

The subfamily Odostomiinae has been recognized as monophyletic.
It includes the tribe Liostomini, a name given to those genera which have an intorted protoconch. The rest of the genera however do not form a single monophyletic taxon.
Subfamily Odostomiinae has been classified as one of eleven recognised subfamilies of the very voluminous gastropod family Pyramidellidae : Odostomiinae, Turbonillinae, Chrysallidinae, Cingulininae, Cyclostremellinae, Sayellinae, Syrnolinae, Eulimellinae, Pyramidellinae, Odostomellinae and Tiberiinae.
In the taxonomy of Bouchet & Rocroi, this subfamily also comprises the subfamilies Chrysallidinae, Cyclostremellinae and Odostomellinae, that they have downgraded to the rank of tribe.
subfamily Odostomiinae Pelseneer, 1928
According to Schander, Van Aartsen and Corgan there are 33 genera in Odostominae with four possible additional genera of uncertain status.

Genera

Genera in the subfamily Odostomiinae include:
tribe Odostomiini
tribe Chrysallidini
tribe Cyclostremellini
tribe Odostomellini

Additional genera

Some additional genera which may belong in the subfamily Odostomiinae are:
This family is found worldwide, from the tropics to the poles.

Shell description

The shell of these snails has a blunt, heterostrophic protoconch, which is often pointed sideways or wrapped up. Most species in the subfamily have shells which are smaller than 13 mm. The texture of these shells is most often smooth but sometimes sculptured in various forms such as ribs and spirals. Their color is mostly white, cream or yellowish, sometimes with red or brown lines. The teleoconch is coiled, but the larval shells are. This results in a sinistrally coiled protoconch. The columella has usually one, but sometimes several, spiral folds. The aperture is closed by an operculum.

Life habits

The Odostomiinae are ectoparasites, feeding mainly on other molluscs and on annelid worms, but some are known to feed on peanut worms and crustaceans.
They do not have a radula. Instead their long proboscis is used to pierce the skin of its prey and suck up its fluids and soft tissues. The eyes on the grooved tentacles are situated toward the base of the tentacles. Between the head and the foot, a lobed process called the mentum is visible. These molluscs are hermaphrodites.