Odostomia loomisi
Encyclopedia
Odostomia loomisi is a species
of sea snail
, a marine
gastropod mollusk in the family
Pyramidellidae
, the pyrams and their allies.
are smooth, deeply obliquely immersed in the first of the succeeding turns, above which only a portion of the tilted edge of the last volution projects. Early post-nuclear whorls are well rounded, later ones flattened, somewhat excurved at the shouldered and beaded summit, and slightly contracted at the sutures. The whorls are marked by strong rounded, tuberculated axial ribs, which are decidedly protractive on all but the last whorl; on this they are only moderately protracted. Of the axial ribs, 14 appear upon the first, 16 upon the second, 20 upon the third, and 24 upon the penultimate turn. In addition to the ribs the whorls are marked between the sutures by four spiral cords, which almost equal the ribs in strength, forming tubercles at their junctions with the axial ribs. On the last whorl and one-half the summit drops below the peripheral keel and leaves this in the suture. The axial ribs, however, terminate at the posterior edge of it, and thus leave it without tubercles. The spaces enclosed by the ribs and cords appear as deep oval pits having their long axis parallel to the cords. Sutures are well marked but not channeled. The base of the body whorl
is long, well rounded, and strongly inflated. It is marked by seven spiral cords, the four anterior to the periphery being equal and equally spaced, the other three growing successively smaller. The channels between the cords are very regular, marked by many slender axial riblets. The oval aperture
is somewhat effuse anteriorly. The posterior angle is obtuse. The outer lip
is thin, showing the external sculpture within. The columella is slender, curved, and reflected, not reenforced by the base.
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 shell is very small, pupiform, vitreous. 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 smooth, deeply obliquely immersed in the first of the succeeding turns, above which only a portion of the tilted edge of the last volution projects. Early post-nuclear whorls are well rounded, later ones flattened, somewhat excurved at the shouldered and beaded summit, and slightly contracted at the sutures. The whorls are marked by strong rounded, tuberculated axial ribs, which are decidedly protractive on all but the last whorl; on this they are only moderately protracted. Of the axial ribs, 14 appear upon the first, 16 upon the second, 20 upon the third, and 24 upon the penultimate turn. In addition to the ribs the whorls are marked between the sutures by four spiral cords, which almost equal the ribs in strength, forming tubercles at their junctions with the axial ribs. On the last whorl and one-half the summit drops below the peripheral keel and leaves this in the suture. The axial ribs, however, terminate at the posterior edge of it, and thus leave it without tubercles. The spaces enclosed by the ribs and cords appear as deep oval pits having their long axis parallel to the cords. Sutures are well marked but not channeled. The base 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 long, well rounded, and strongly inflated. It is marked by seven spiral cords, the four anterior to the periphery being equal and equally spaced, the other three growing successively smaller. The channels between the cords are very regular, marked by many slender axial riblets. The oval 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 somewhat effuse anteriorly. The posterior angle is obtuse. 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, not reenforced by the base.