Odostomia grammatospira
Encyclopedia
Odostomia grammatospira is a species
of sea snail
, a marine
gastropod mollusk in the family
Pyramidellidae
, the pyrams and their allies.
are small, forming a depressed helicoid spire
, which is a little more than half obliquely immersed in the first of the succeeding turns. The eight post-nuclear whorls are moderately rounded, marked by four strong, equal, and almost equally spaced spiral cords which are separated by three well-incised spiral grooves. The suture is subchanneled. The periphery of the body whorl
is marked by a depressed cord which is not quite as strong as those between the sutures. The base of the shell is somewhat attenuated, well rounded. It is marked by ten spiral cords which grow successively weaker and
closer spaced from the periphery toward the umbilical area, disappearing altogether on the extreme anterior portion. The spaces between the spiral cords on the spire and the base are marked by slender axial threads. The aperture
is oval, effuse anteriorly. The posterior angle is acute. The outer lip
is thin, showing the external sculpture within, rendered wavy by the keels. The columella is stout, reflected, re-enforced by the base, and provided with a weak fold at its insertion. The parietal wall is glazed with a faint 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-conic shell is semitranslucent and measures 5.8 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, forming a depressed helicoid spire
Spire (mollusc)
A spire is a descriptive term for part of the coiled shell of mollusks. The word is a convenient aid in describing shells, but it does not refer to a very precise part of shell anatomy: the spire consists of all of the whorls except for the body whorl...
, which is a little more than half obliquely immersed in the first of the succeeding turns. The eight post-nuclear whorls are moderately rounded, marked by four strong, equal, and almost equally spaced spiral cords which are separated by three well-incised spiral grooves. The suture is subchanneled. 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 depressed cord which is not quite as strong as those between the sutures. The base of the shell is somewhat attenuated, well rounded. It is marked by ten spiral cords which grow successively weaker and
closer spaced from the periphery toward the umbilical area, disappearing altogether on the extreme anterior portion. The spaces between the spiral cords on the spire and the base are marked by slender axial threads. 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 oval, 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, rendered wavy by the keels. The columella is stout, reflected, re-enforced by the base, and provided with a weak fold at its insertion. The parietal wall is glazed with a faint callus.