Odostomia fetella
Encyclopedia
Odostomia fetella is a species
of sea snail
, a marine
gastropod mollusk in the family
Pyramidellidae
, the pyrams and their allies.
are small, obliquely two-thirds immersed in the first of the succeeding turns. The seven post-nuclear whorls are well rounded, moderately contracted at the sutures and slightly shouldered at the summit. They are marked by four strong flattened cords which grow successively a little weaker from the summit to the periphery, separated by narrow, deeply incised spiral grooves. The periphery of the body whorl
is marked by a broad, flat cord somewhat wider than the first supra-peripheral one. The base of the body whorl is somewhat attenuated anteriorly, well rounded, marked by eleven equal and equally narrow, rounded, spiral cords. In addition to this sculpture
, there are many very fine incised spiral lines and decidedly retractive axial lines of growth on the spire and base. The
aperture
is broadly oval and slightly effuse anteriorly. The posterior angle is acute. The outer lip
is thin, showing the external sculpture within. The columella is moderately strong, slightly curved, somewhat reflected. It is completely re-enforced by the base and provided with a strong fold at its insertion. The parietal wall is covered by a thin callus.
, California, to San Ignacio Lagoon, Lower California.
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 very elongate-ovate shell is milk-white. It measures 4.4 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, obliquely two-thirds immersed in the first of the succeeding turns. The seven post-nuclear whorls are well rounded, moderately contracted at the sutures and slightly shouldered at the summit. They are marked by four strong flattened cords which grow successively a little weaker from the summit to the periphery, separated by narrow, deeply incised spiral grooves. 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 broad, flat cord somewhat wider than the first supra-peripheral one. The base of the body whorl is somewhat attenuated anteriorly, well rounded, marked by eleven equal and equally narrow, rounded, spiral cords. In addition to this sculpture
Sculpture (mollusc)
The sculpture of a mollusc shell is the three-dimensional ornamentation on the outer surface, as distinct from the basic shape of the shell itself or colouration. Sculpture may be concave as well as convex. Sometimes it has microscopic detail. Sculpture refers to the calcareous outer layer, not the...
, there are many very fine incised spiral lines and decidedly retractive axial lines of growth on the spire and base. 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 broadly oval and slightly 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 moderately strong, slightly curved, somewhat reflected. It is completely re-enforced by the base and provided with a strong fold at its insertion. The parietal wall is covered by a thin callus.
Distribution
This species occurs in the pacific Ocean from San PedroSan Pedro Bay (California)
San Pedro Bay is an inlet on the Pacific Ocean coast of southern California, United States. It is the site of the Port of Los Angeles and the Port of Long Beach, which together form the fifth-busiest port facility in the world and easily the busiest in the Western Hemisphere...
, California, to San Ignacio Lagoon, Lower California.