Odostomia benthina
Encyclopedia
Odostomia benthina is a species
of sea snail
, a marine
gastropod mollusk in the family
Pyramidellidae
, the pyrams and their allies.
are small, deeply obliquely immersed in the first post-nuclear turn, above which only the tilted edge of the last volution projects. The six post-nuclear whorls are well rounded, marked by slender, nodulous, retractive axial ribs, wliich terminate at the posterior extremity of the supra-peripheral cord, leaving this smooth. Of these ribs about 35 occur upon the first whorl, 28 upon the second and third, 22 upon the fourth, and 26 upon the penultimate turn. In addition to the axial ribs, the whorls are marked by five strong, spiral cords, the junction of which with the ribs form tubercles. The periphery of the body whorl
is marked by a groove. The base of the shell is well rounded, ornamented with seven equal and equally spaced spiral cords, the grooves between which are marked by fine, raised axial threads.
The aperture
is pyriform, somewhat effuse anteriorly. The posterior angle is acute. The outer lip
is thin, showing the external sculpture within. The columella is slender, curved, and reflected, provided with an oblique fold at its insertion. The parietal wall is covered with a thin callus.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of sea snail
Sea snail
Sea snail is a common name for those snails that normally live in saltwater, marine gastropod molluscs....
, a marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
gastropod mollusk in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Pyramidellidae
Pyramidellidae
Pyramidellidae, common name the pyram family, or pyramid shells, is a voluminous taxonomic family of mostly small and minute ectoparasitic sea snails, marine heterobranch gastropod molluscs or micromolluscs....
, the pyrams and their allies.
Description
The elongate-conic shell is white. It measures 4.8 mm. The nuclear whorlsWhorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the...
are small, deeply obliquely immersed in the first post-nuclear turn, above which only the tilted edge of the last volution projects. The six post-nuclear whorls are well rounded, marked by slender, nodulous, retractive axial ribs, wliich terminate at the posterior extremity of the supra-peripheral cord, leaving this smooth. Of these ribs about 35 occur upon the first whorl, 28 upon the second and third, 22 upon the fourth, and 26 upon the penultimate turn. In addition to the axial ribs, the whorls are marked by five strong, spiral cords, the junction of which with the ribs form tubercles. The periphery of the body whorl
Body whorl
Body whorl is part of the morphology of a coiled gastropod mollusk.- In gastropods :In gastropods, the body whorl, or last whorl, is the most recently-formed and largest whorl of a spiral or helical shell, terminating in the aperture...
is marked by a groove. The base of the shell is well rounded, ornamented with seven equal and equally spaced spiral cords, the grooves between which are marked by fine, raised axial threads.
The aperture
Aperture (mollusc)
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....
is pyriform, somewhat effuse anteriorly. The posterior angle is acute. The outer lip
Lip (gastropod)
In the shell of a gastropod mollusk , the margin of the aperture is called the lip or the peristome. In other words, this is a term used to describe part of gastropod shell anatomy....
is thin, showing the external sculpture within. The columella is slender, curved, and reflected, provided with an oblique fold at its insertion. The parietal wall is covered with a thin callus.