Odostomia meta
Encyclopedia
Odostomia meta is a species
of sea snail
, a marine
gastropod mollusk in the family
Pyramidellidae
, the pyrams and their allies.
. The nuclear whorls
are small, strongly obliquely immersed in the first post-nuclear whorl; only a portion of the last volution is visible. The six post-nuclear whorls overhang somewhat. They are rather high between the sutures, shouldered at the summit, flattened, suddenly contracted below the periphery. The summits of succeeding whorls fall considerably anterior to the periphery, which appears decidedly angular. The whorls are marked by strong axial ribs which extend undiminished over the angular periphery and the base of the body whorl
to the umbilical region. Sixteen of these ribs occur upon the second, twenty-two upon the fourth and the penultimate whorl. The ribs are slightly constricted just below the summit, which gives them a beaded appearance. The intercostal spaces are about twice as wide as the ribs, crossed by two closely placed, raised spiral threads, the anterior one of which marks the angulation of the periphery. The junction of ribs and the spiral threads is subnodulose. The base of the shell is moderately long, narrowly umbilicate. The aperture
is suboval. The posterior angle is obtuse. The outer lip
is rather thick. The columella is strongly curved, with a prominent oblique fold near its insertion. The parietal wall is covered with a heavy callus, which gives the periostracum a completed aspect.
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 thin, milk-white shell is very small, measuring 2.9 mm. It is turrited, with channeled sutures and an obtuse apexApex (mollusc)
Apex is an anatomical term for the tip of the mollusc shell of a gastropod, scaphopod, or cephalopod mollusc.-Gastropods:The word "apex" is most often used to mean the tip of the spire of the shell of a gastropod...
. The nuclear whorls
Whorl (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, strongly obliquely immersed in the first post-nuclear whorl; only a portion of the last volution is visible. The six post-nuclear whorls overhang somewhat. They are rather high between the sutures, shouldered at the summit, flattened, suddenly contracted below the periphery. The summits of succeeding whorls fall considerably anterior to the periphery, which appears decidedly angular. The whorls are marked by strong axial ribs which extend undiminished over the angular periphery and 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...
to the umbilical region. Sixteen of these ribs occur upon the second, twenty-two upon the fourth and the penultimate whorl. The ribs are slightly constricted just below the summit, which gives them a beaded appearance. The intercostal spaces are about twice as wide as the ribs, crossed by two closely placed, raised spiral threads, the anterior one of which marks the angulation of the periphery. The junction of ribs and the spiral threads is subnodulose. The base of the shell is moderately long, narrowly umbilicate. 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 suboval. 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 rather thick. The columella is strongly curved, with a prominent oblique fold near its insertion. The parietal wall is covered with a heavy callus, which gives the periostracum a completed aspect.