Odostomia fasciata
Encyclopedia
Odostomia fasciata is a species
of sea snail
, a marine
gastropod mollusk in the family
Pyramidellidae
, the pyrams and their allies.
are small, obliquely immersed in the first of the succeeding turns. The five post nuclear whorls are moderately rounded, ornamented by decidedly retractive axial ribs which practically terminate at the posterior edge of the supraperipheral spiral keel. Of these ribs, 12 occur upon the first, 14 upon the second, 18 upon the third, and 22 upon the penultimate turn. In addition to these ribs the whorls are marked by four spiral keels between the sutures which equal the ribs in strength and render the three anterior to the summit tuberculated at their junction, the fourth one being smooth. The sutures are strongly channeled. The periphery of the body whorl
is marked by a groove. The base of the shell is well rounded, marked by six slender spiral keels, which are a little less strongly developed and more closely spaced at the umbilical area than at the periphery. The grooves separating these keels are about twice as wide as the keels, crossed by slender axial threads which correspond to the ribs. The aperture
is ovate, somewhat effuse anteriorly. The posterior angle is obtuse. The outer
lip
is sinuous, thin and shows the external sculpture within. The columella is moderately strong, reflected, and provided with a slender fold at its insertion. The parietal wall is glazed 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-ovate shell is white. It measures 2.1 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 immersed in the first of the succeeding turns. The five post nuclear whorls are moderately rounded, ornamented by decidedly retractive axial ribs which practically terminate at the posterior edge of the supraperipheral spiral keel. Of these ribs, 12 occur upon the first, 14 upon the second, 18 upon the third, and 22 upon the penultimate turn. In addition to these ribs the whorls are marked by four spiral keels between the sutures which equal the ribs in strength and render the three anterior to the summit tuberculated at their junction, the fourth one being smooth. The sutures are strongly channeled. 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, marked by six slender spiral keels, which are a little less strongly developed and more closely spaced at the umbilical area than at the periphery. The grooves separating these keels are about twice as wide as the keels, crossed by slender axial threads which correspond to the ribs. 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 ovate, 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 sinuous, thin and shows the external sculpture within. The columella is moderately strong, reflected, and provided with a slender fold at its insertion. The parietal wall is glazed with a thin callus.