Crosseola striata

Crosseola striata
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Clade:	Vetigastropoda
Order:	Trochida
Superfamily:	Trochoidea
Family:	Conradiidae
Genus:	Crosseola
Species:	C. striata
Binomial name
	Crosseola striata; Watson, 1883
Synonyms
	Crossea agulhasensisThiele, J. 1925;

Last updated March 22, 2019

Crosseola striata is a species of small sea snail or micromollusc, a marine gastropod mollusc in the family Conradiidae.^[1]

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 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 hierarchical 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".

Description

(Original description by R. Boog Watson) The height of the shell attains 1.5 mm, its diameter 1.3 mm. The very small, porcellaneous white shell has a turbinate shape. It is spirally striated, with a raised, subscalar spire, a minute rounded apex, which is tabulated, with the extreme tip just visible, a tumid body whorl, and a small strongly bordered umbilicus.

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.

The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk.

Sculpture: Longitudinals—there are microscopic lines of growth which gather into puckers below the suture.

Sculpture is a feature of many of the shells of mollusks. It is three-dimensional ornamentation on the outer surface of the shell, as distinct from either the basic shape of the shell itself or the pattern of colouration, if any. Sculpture is a feature found in the shells of gastropods, bivalves, and scaphopods. The word "sculpture" is also applied to surface features of the aptychus of ammonites, and to the outer surface of some calcareous opercula of marine gastropods such as some species in the family Trochidae.

Spirals—there are furrows broadish and square-cut, parted by flat raised surfaces of about twice their breadth. These extend to below the periphery, but not to the base, the most of which is smooth. Round the umbilicus is a high raised thread, which relatively to the size of the shell is enormous.

The four whorls are well rounded, and a very little tabulated below the suture. The body whorl is tumid. The suture is strongly marked, but hardly impressed. The aperture is round, but a little gibbous, bluntly pointed above. The thin, well arched outer lip is scarcely patulous.The inner lip is regularly curved from the corner of the aperture to the point of the columella, which is arched, with a thin inner edge parting the aperture from the umbilicus and joining the outer lip, while round the umbilicus twists the strong marginal cord which runs out into a strong blunt tooth at the tip of the columella. The deep umbilicus is small but strongly marked.^[2]

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.

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 marine species occurs off South Africa and Australia (Queensland, Northern Territory)

South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by 2,798 kilometres (1,739 mi) of coastline of Southern Africa stretching along the South Atlantic and Indian Oceans; to the north by the neighbouring countries of Namibia, Botswana, and Zimbabwe; and to the east and northeast by Mozambique and Eswatini (Swaziland); and it surrounds the enclaved country of Lesotho. South Africa is the largest country in Southern Africa and the 25th-largest country in the world by land area and, with over 57 million people, is the world's 24th-most populous nation. It is the southernmost country on the mainland of the Old World or the Eastern Hemisphere. About 80 percent of South Africans are of Sub-Saharan African ancestry, divided among a variety of ethnic groups speaking different African languages, nine of which have official status. The remaining population consists of Africa's largest communities of European (White), Asian (Indian), and multiracial (Coloured) ancestry.

Queensland is the second-largest and third-most populous state in the Commonwealth of Australia. Situated in the north-east of the country, it is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean. To its north is the Torres Strait, with Papua New Guinea located less than 200 km across it from the mainland. The state is the world's sixth-largest sub-national entity, with an area of 1,852,642 square kilometres (715,309 sq mi).

The Northern Territory is an Australian territory in the central and central northern regions of Australia. It shares borders with Western Australia to the west, South Australia to the south, and Queensland to the east. To the north, the territory looks out to the Timor Sea, the Arafura Sea and the Gulf of Carpentaria, including Western New Guinea and other Indonesian islands. The NT covers 1,349,129 square kilometres (520,902 sq mi), making it the third-largest Australian federal division, and the 11th-largest country subdivision in the world. It is sparsely populated, with a population of only 246,700, making it the least-populous of Australia's eight states and major territories, with fewer than half as many people as Tasmania.

References

Watson, R.B. 1883. Mollusca of "H.M.S. Challenger" expedition. Journal of the Linnean Society of London, Zoology 16: 494
Thiele, J. 1925. Gastropoda der Deutschen Tiefsee-Expedition. II. Teil. Wissenschaftliche Ergebnisse der Deutschen Tiefsee-Expedition auf dem Dampfer "Valdivia" 1898–1899 17(2): 35-382, pls 313-346
Cotton, B.C. 1959. South Australian Mollusca. Archaeogastropoda. Handbook of the Flora and Fauna of South Australia. Adelaide : South Australian Government Printer 449 pp.

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[1] Carole S. Hickman, Crosseolidae, a New Family of Skeneiform Microgastropods and Progress Toward Definition of Monophyletic Skeneidae; American Malacological Bulletin 31(1):1-16. 2013

[2] The Journal of the Linnean Society of London v.16 (1881-1883) Archived 2013-09-22 at the Wayback Machine .

Crosseola striata

Contents

Description

Distribution

Related Research Articles

References