Black Nerite (or Black Crower)
Phylum: Mollusca, Class: Gastropoda, Order: Cycloneritida, Family: Neritidae, Genus: Nerita, Species: N. atramentosa · Neritidae (Nerite family) · Gastropod (univalve); globose/spiral shape with a very low spire and a thickened outer lip.
Species
Nerita atramentosa (Confidence Level: 95%)
Shell Type
Gastropod (univalve); globose/spiral shape with a very low spire and a thickened outer lip.
Family
Neritidae (Nerite family)
Size
Approximately 15-25mm (0.6-1.0 inch) in diameter. This specimen appears to be a mature adult within the standard size range for the South-East Queensland coast.
Color & Pattern
Uniformly charcoal black to deep matte grey-black on the exterior. The interior (not fully visible) is typically white with a smooth, concave columellar area. This specimen shows slight surface wear with a small white patch where the outer black layer has eroded.
Rarity
Very Common; one of the most abundant gastropods found on rocky platforms in the Brisbane/Sandgate region.
Habitat
Found in the high-intertidal zone on rocky shores. They prefer stable rocks where they can graze on algae during high tide and cluster in damp crevices or under ledges during low tide to prevent desiccation.
Geographic Range
Common along the coastlines of Southern and Eastern Australia, including Queensland, New South Wales, Victoria, and Western Australia, as well as New Zealand.
Description
A robust, thick-walled gastropod shell with a smooth, matte finish. The shell is globose (rounded) with a very low, almost flat spire and a large body whorl. The surface lacks prominent ribs, appearing nearly smooth to the naked eye but possessing fine growth lines. It is a quintessential 'rocky shore' shell, built to withstand heavy wave action.
Key Features
Charcoal black coloration, smooth globose shape, white aperture (mouth), and a distinctive flat, smooth columellar deck with no teeth (unlike some other Nerita species).
Collector Value
Low monetary value ($1-$2 USD) as they are extremely common. However, they are a staple specimen for any Australian temperate or subtropical shell collection due to their iconically dark pigment.
Condition Notes
Beach-worn condition (Fair to Good). The shell shows significant erosion of the apex and a 'chip' or wear mark exposing the white calcium carbonate beneath. The matte texture suggests it has been rolled in the sand and surf at Sandgate for some time.
Interesting Facts
Nerita atramentosa is a 'homing' snail; after grazing on algae during the night or high tide, individuals often return to the exact same crevice on their rock. They are highly adapted to tolerate heat and water loss, effectively 'sealing' themselves to the rock with their operculum.
Ecological Role
Important primary consumer (herbivore) that controls algal growth on rocky substrates. They serve as a food source for shorebirds and predatory crabs.
Similar Species
Nerita plicata (which is ribbed and lighter) and Nerita albicilla (which has a bumpy columella/deck). It is easily distinguished from the 'Bleeding Tooth' Nerite of the Caribbean by its lack of teeth and solid black color.
Beach Finding Tips
Search the rocky groynes or pebble sections of Sandgate and Brighton at low tide. Look for them clustered in the shade of rocks or tucked into cracks where moisture remains.
Notes
Brighton Sandgate beach Brisbane