Odostomia marginata
Encyclopedia
Odostomia marginata is a species
of sea snail
, a marine
gastropod mollusk in the family
Pyramidellidae
, the pyrams and their allies.
are small, two and one-half, forming: a depressed helicoid spire, whose axis is at right angles to that of the succeeding turns, in the first of which it is about one-fourth immersed. Post-nuclear whorls are flattened, moderately contracted at the sutures and slightly shouldered at the summit, marked by very strong, lamellar, somewhat retractive axial ribs, of which 14 occur upon all of the whorls. The termination of these ribs form cusps at the summits. Intercostal spaces are four times as wide as the ribs, marked by six equal and equally spaced incised lines, the space between the summit and the first line below it appearing as a thickened cord. The sutures are well impressed. The periphery of the body whorl
and base is well rounded, marked by the strong continuation of the axial ribs and about five incised spiral lines. The aperture
is ovate. The posterior angle is acute. The outer lip
is thin, showing the external sculpture within. The columella is stout, slightly curved and somewhat r volute. The parietal wall is covered by a very strong 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 small shell is elongate-conic, rather stout and semitranslucent. 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, two and one-half, forming: a depressed helicoid spire, whose axis is at right angles to that of the succeeding turns, in the first of which it is about one-fourth immersed. Post-nuclear whorls are flattened, moderately contracted at the sutures and slightly shouldered at the summit, marked by very strong, lamellar, somewhat retractive axial ribs, of which 14 occur upon all of the whorls. The termination of these ribs form cusps at the summits. Intercostal spaces are four times as wide as the ribs, marked by six equal and equally spaced incised lines, the space between the summit and the first line below it appearing as a thickened cord. The sutures are well impressed. 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...
and base is well rounded, marked by the strong continuation of the axial ribs and about five incised spiral lines. 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. 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 stout, slightly curved and somewhat r volute. The parietal wall is covered by a very strong callus.