Asthelys simplex

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Asthelys simplex
Asthelys simplex 001.jpg
Drawing with an apertural view of a shell of Asthelys simplex
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Clade: Vetigastropoda
Superfamily: Seguenzioidea
Family: Seguenziidae
Subfamily: Asthelysinae
Genus: Asthelys
Species:
A. simplex
Binomial name
Asthelys simplex
(Watson, 1879) [1]
Synonyms [2]
  • Basilissa simplex Watson, 1879 (original description)

Asthelys simplex is a species of extremely small deep water sea snail, a marine gastropod mollusk in the family Seguenziidae. [2] [3]

In biology, a species ( ) is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more closely they represent problematic species concepts. For example, the boundaries between closely related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, and in a ring species. Also, among organisms that reproduce only asexually, the concept of a reproductive species breaks down, and each clone is potentially a microspecies.

Sea snail common name for snails that normally live in saltwater

Sea snail is a common name for snails that normally live in salt water, in other words marine gastropods. The taxonomic class Gastropoda also includes snails that live in other habitats, such as land snails and freshwater snails. Many species of sea snails are edible and exploited as food sources by humans.

Family is one of the eight major hierarcical taxonomic ranks in Linnaean taxonomy; it is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as being the "walnut family".

Contents

Description

The shell grows to a height of 6.5 mm. The shell is a rather narrow flat-based cone that is sharply angulated. The shell is small, thin, delicate, smooth, glassy, and nacreous under a thin white calcareous surface.

Sculpture: There are longitudinals, which are faint, hairlike and sinuated, showing the old lines of growth. The whole surface has traces of faint, rounded, and irregular spirals. At the bottom of each whorl is a flat puckered band about 0.25 mm. broad, whose upper edge projects sharply, especially on the upper whorls, and whose lower edge is a slight narrow flange, which forms a sharp carina at the periphery. This band forms the upper border of the suture, which is further marginated below by two not continuous rounded threads occupying the top edge of each whorl. The base of the shell is covered by about fourteen rounded ridges and furrows, which are rather stronger toward the center, the last one, forming the edge of the umbilicus, being specially so.

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 ammonites.

In anatomy, a suture is a fairly rigid joint between two or more hard elements of an organism, with or without significant overlap of the elements.

Umbilicus (mollusc)

The umbilicus of a shell is the axially aligned, hollow cone-shaped space within the whorls of a coiled mollusc shell. The term umbilicus is often used in descriptions of gastropod shells, i.e. it is a feature present on the ventral side of many snail shells, including some species of sea snails, land snails, and freshwater snails.

Color: The surface is a dead slightly creamy white, formed by a thin calcareous layer through which the underlying nacre shines.

The spire is high and conical. The apex broken. The 8 whorls (reckoning the first two as broken) show a slow and regular increase till the last, which enlarges rapidly. They are perfectly flat, with an upper and lower border, sharply angulated and carinated at the periphery, slightly convex but still very flat on the base, with a blunted angulated and carinated umbilical edge. The suture is linear, almost invisible, marginated above and below. The aperture is perpendicular, rhomboidal, with the columella and basal edges nearly equal, and the columella and outer lip nearly parallel. The outer lip is sharp and thin, not patulous, not descending, advancing at its junction with the body whorl, then retreating so as to form the broad open sinus, acute angled at the periphery, slightly arched across the base, nicked close to the point of the pillar. The columellar lip is arched, strengthened by a thin pad; reverted on the umbilicus so as to leave a slight groove behind it, it has a slight tooth in front. From the body whorl it bends very much over to the left, so as largely to cover the umbilicus, and then it curves over to the right to join the outer lip on the base at an obtuse angle. The umbilicus is small, oblique edged, funnel-shaped, nearly covered by the columellar lip, contracted within, scored with hair-like lines of growth. [4]

Spire (mollusc)

A spire is a part of the coiled shell of molluscs. The spire consists of all of the whorls except for the body whorl. Each spire whorl represents a rotation of 360°. A spire is part of the shell of a snail, a gastropod mollusc, a gastropod shell, and also the whorls of the shell in ammonites, which are fossil shelled cephalopods.

In anatomy, an apex is part of the shell of a mollusk. The apex is the pointed tip of the shell of a gastropod, scaphopod, or cephalopod.

Aperture (mollusc) The main opening of the shell, where the head-foot part of the body of the animal emerges

The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where the head-foot part of the body of the animal emerges for locomotion, feeding, etc.

Distribution

This species occurs off the mouth of La Plata, Uruguay at a depth of 3,500 m.

La Plata City in Buenos Aires, Argentina

La Plata is the capital city of Buenos Aires Province, Argentina. According to the 2001 census [INDEC], it has a population of 765,378 and its metropolitan area has 899,523 inhabitants.

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References

  1. Watson, J. L. S. L. xiv, p. 595 ; Challenger Rep., p. 98, t. 7, f. 6.
  2. 1 2 Rosenberg, G. (2012). Asthelys simplex (Watson, 1879). Retrieved through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=492405 on 2013-04-14
  3. Natural History Museum, London (NHM): Collections Management Database System
  4. Tryon (1889), Manual of Conchology XI, Academy of Natural Sciences, Philadelphia