Nerita melanotragus, common name

Common name

A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...

 black nerite, is a medium-sized 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 mollusc 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...

 Neritidae

Neritidae

Neritidae, common name the nerites, is a taxonomic family of small to medium-sized saltwater and freshwater snails which have a gill and a distinctive operculum, marine, brackish water and freshwater gastropod mollusks in the order Neritoida....

, the nerites.

There has been some confusion over the taxonomy

Taxonomy

Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...

 of the Nerita genus in the Pacific region, however Nerita atramentosa

Nerita atramentosa

Nerita atramentosa, common name the black nerite, is a medium-sized sea snail, a marine gastropod mollusc in the family Neritidae, the nerites....

and Nerita melanotragus are now recognised as separate species (the two have often been considered to be the same species).

Distribution

This nerite is endemic

Endemic (ecology)

Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...

 to the southern Pacific, including the south-eastern coast of Australia (Queensland

Queensland

Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. 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...

, New South Wales

New South Wales

New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

, Victoria

Victoria (Australia)

Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....

, Lord Howe Island

Lord Howe Island

Lord Howe Island is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, directly east of mainland Port Macquarie, and about from Norfolk Island. The island is about 11 km long and between 2.8 km and 0.6 km wide with an area of...

, Norfolk Island

Norfolk Island

Norfolk Island is a small island in the Pacific Ocean located between Australia, New Zealand and New Caledonia. The island is part of the Commonwealth of Australia, but it enjoys a large degree of self-governance...

, northern New Zealand and the Kermadec Islands

Kermadec Islands

The Kermadec Islands are a subtropical island arc in the South Pacific Ocean northeast of New Zealand's North Island, and a similar distance southwest of Tonga...

.

Habitat

This species is commonly found on intertidal rocks, particularly in the mid to upper intertidal zone. It prefers to attach to sloped or vertical rock surfaces, or hang from the underside of rocks. This may be a method of thermoregulation

Thermoregulation

Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different...

, because if N. atramentosa is on a horizontal surface, it would absorb the maximum solar radiation, whereas on sloped or vertical surfaces it absorbs less energy (and thus heat).

Shell description

The shell is of moderate size, very solid, globose-oval, and smooth except for weak shallowly incised spiral lines. The external shell colour is black, but 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 white, except for a narrow black border. Once shells get over about 26mm they start to wear down and typically have knotched sides and a white wear on the right hand side of the shell.

The operculum

Operculum (gastropod)

The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...

 is granular, pinkish-lilac, with two spiral bands of black.

The shell height is up to 30 mm, and width 32 mm.

Genetics

An almost complete sequence of the mitochondrial DNA

Mitochondrial DNA

Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...

 of this species was analyzed by Castro & Colgan (2010).

External links

• Waters J. M., King T. M., O'Loughlin P. M. & Spencer H. G. (2005). "Phylogeographic disjunction in an abundant high-dispersal littoral gastropod". Molecular Ecology 2789-2802. doi:10.1111/j.1365-294X.2005.02635.x, PDF.