Black Nerite, Crow Nerite
Kingdom: Animalia; Phylum: Mollusca; Class: Gastropoda; Order: Cycloneritida; Family: Neritidae; Genus: Nerita; Species: Nerita atramentosa · Neritidae (Nerite family) · Gastropod (univalve); Globose/Spiral shape; Single shell with an eroded apex in this specimen.
Species
Nerita atramentosa (Confidence Level: 90%)
Shell Type
Gastropod (univalve); Globose/Spiral shape; Single shell with an eroded apex in this specimen.
Family
Neritidae (Nerite family)
Size
The specimen appears to be approximately 15-20mm in diameter. This is within the typical adult range of 10-30mm for this Australian species.
Color & Pattern
Uniform charcoal black to deep bluish-grey exterior. The surface appears matte and slightly eroded. Interior (not visible) usually features a white aperture with a smooth, black columellar deck.
Rarity
Very Common. These are among the most frequently encountered shells on rocky Australian shores and mudflats.
Habitat
Strongly intertidal; typically found on high-tide rocks, in crevices, or on mudflats. It is a marine species capable of surviving long periods of exposure during low tide.
Geographic Range
Common along the coastline of Australia, particularly from Queensland (including Brisbane/Sandgate) south through New South Wales to Tasmania and Western Australia.
Description
A sturdy, thick-walled globose shell with a low spire. The exterior is characterized by very fine spiral growth lines, though these are often worn smooth by wave action and sand. The shell is designed to withstand heavy surf and prevent desiccation.
Key Features
Ovoid/globose shape, uniform jet-black coloration, and a lack of the heavy ribbing found in many other Nerita species. The smooth black 'deck' (columellar area) is a diagnostic trait for the Australian Nerita atramentosa.
Collector Value
Minimal financial value (less than $1 USD). It is primarily valued as a representative local specimen for educational collections or as a souvenir of the Brisbane coastline.
Condition Notes
Fair. The shell shows significant environmental wear (erosion), typical of beach-found specimens in high-energy areas like Sandgate. The apex is worn down, and there are small calcified deposits on the surface. Collectibility grade: Fair/Field Grade.
Interesting Facts
The Black Nerite is a herbivore that 'grazes' on algae or biofilms covering rocks. They have a specialized ability to trap water inside their shell to breathe during low tide, acting like a tiny portable aquarium.
Ecological Role
Important primary consumer in the intertidal zone. By grazing on algae, they prevent overgrowth on rocks. They serve as a food source for shorebirds and predatory crabs.
Similar Species
Nerita melanotragus (found in New Zealand/Eastern Aus, often synonymized but subtly different), and Nerita plicata (which is lighter in color with much heavier ribs).
Beach Finding Tips
Look along the high tide line among rocky outcrops or in the muddy sand near mangroves in Sandgate/Brighton. They are easiest to find when the tide is receding and they are exposed on rock surfaces.
Notes
Brighton Sandgate beach Brisbane