General Description

Black shell. Flattened spire with expanded final whorl (body whorl). Shell mostly smooth but has very fine, almost indistinguishable, spiral lines, more than 30. Large, semicircular aperture with white inner lip. Operculum (shelly flap covering the shell aperture) black and globose. Shell up to 3 cm long. Can be difficult to distinguish from Nerita melanotragus which is externally very similar. The most obvious difference is the different colour and shape opercula and the colour of the inner lip.

Biology

Black Nerites are grazers, feeding on thin microalgae films on rock surfaces. They are often found in high numbers, forming dense clusters of individuals. They are thought to live for around 3 years. Black Nerites have two sexes and internal fertilisation. Females deposit egg capsules, which are white, slightly elongated domes, on the underside of stones in rock pools. These egg capsules contain up to 40 eggs and hatch planktonic larvae which can travel quite long distances before settling and metamorphosing. Until 2007 all Black Nerites in Australia were called Nerita atramentosa, but now two species with different but overlapping ranges are recognised. em>Nerita atramentosa occurs from New South Wales to Western Australia while the other species, Nerita melanotragus, occurs from Queensland to South Australia.

Distribution

Southern mainland Australia and Tasmania.

Habitat

Mid to high intertidal areas of rocky shores.

More Information