Odostomia galapagensis
Encyclopedia
Odostomia galapagensis is a species
of sea snail
, a marine
gastropod mollusk in the family
Pyramidellidae
, the pyrams and their allies.
number at least two, forming a depressed helicoid spire, which is slightly tilted to one side and for the greater part immersed in the first of the succeeding turns. The tilted edge of the nucleus shows traces of spiral lirations. The six post-nuclear whorls are appressed at the summit They are ornamented by two very strong, lamelliform keels, whose edges are decidedly upturned, forming deeply channeled troughs. The posterior of the two lamellae is feebly crenulated. The periphery of the [body whorl]] is marked by a spiral keel which is about half as strong as those between the sutures. A fourth keel, a little weaker than the peripheral one, marks tlie middle of the base. The deep concave channels between the keels are marked by strong lines of growth. The sutures are strongly channeled. The aperture
is irregularly oval. The posterior angle is obtuse. The outer lip
is rendered angular by the spiral keels. The columella is stout, curved, re-enforced by the base. The parietal wall is covered 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 conic shell is, milk-white. It measures 2.0 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...
number at least two, forming a depressed helicoid spire, which is slightly tilted to one side and for the greater part immersed in the first of the succeeding turns. The tilted edge of the nucleus shows traces of spiral lirations. The six post-nuclear whorls are appressed at the summit They are ornamented by two very strong, lamelliform keels, whose edges are decidedly upturned, forming deeply channeled troughs. The posterior of the two lamellae is feebly crenulated. The periphery of the [body whorl]] is marked by a spiral keel which is about half as strong as those between the sutures. A fourth keel, a little weaker than the peripheral one, marks tlie middle of the base. The deep concave channels between the keels are marked by strong lines of growth. The sutures are strongly channeled. 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 irregularly oval. 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 rendered angular by the spiral keels. The columella is stout, curved, re-enforced by the base. The parietal wall is covered with a thin callus.