Dog Whelk (also known as the Dog Bivalve-mimic or Mud Snail)
Phylum: Mollusca, Class: Gastropoda, Order: Neogastropoda, Family: Nassariidae, Genus: Nassarius, Species: dorsatus · Nassariidae (Dog Whelks or Nassa mud snails) · Gastropod (univalve); Spiral/Ovates shape. This specimen is a heavily eroded/broken fragment of the body whorl and spire.
Species
Nassarius dorsatus (Confidence: High, based on local Brisbane beach occurrence)
Shell Type
Gastropod (univalve); Spiral/Ovates shape. This specimen is a heavily eroded/broken fragment of the body whorl and spire.
Family
Nassariidae (Dog Whelks or Nassa mud snails)
Size
Approximately 12-15mm in its current broken state. Whole adults typically range from 20-35mm.
Color & Pattern
Features a creamy-white to tan base with distinct broad brown/chocolate axial bands and faint spiral lining. The color appears sun-bleached and weathered from time in the surf.
Rarity
Very Common (This is one of the most frequently encountered scavenger snails on mudflats in the Brisbane/Moreton Bay area).
Habitat
Intertidal and shallow subtidal zones, specifically favoring silty sand or mudflats near mangroves and estuaries, common in Moreton Bay.
Geographic Range
Tropical and subtropical Indo-West Pacific, following the Australian coastline from Northern New South Wales up through Queensland (including Sandgate) to Northern Australia.
Description
A robust, globose gastropod fragment. The shell features thick walls characteristic of the Nassa family, designed to withstand the crushing forces of high-energy intertidal zones. While broken, the specimen shows the characteristic smooth, polished texture and rounded whorls of the species.
Key Features
Distinguished by its heavy, polished shell, broad brown banding, and a distinctive 'callus' (thickened enamel) that would have been present near the aperture in a whole specimen.
Collector Value
Minimal. While whole, high-gloss specimens are attractive for beginner collections, beach-worn fragments have little monetary value. Whole specimens typically retail for $1-$3 USD.
Condition Notes
Poor (Beach worn/Fragment). The apex (tip) and much of the aperture (opening) are missing. Significant erosion has rounded the edges of the break, indicating it has been tumbling in the tide for some time. Collectibility: Study grade only.
Interesting Facts
Known as 'zombie snails,' these creatures spend much of their time buried in the sand with only a long siphon protruding like a snorkel to sniff out decaying animal matter. They are highly efficient scavengers, often converging in hundreds on a single piece of carrion.
Ecological Role
Crucial 'clean-up crews' for the marine environment. By scavenging dead fish and invertebrates, they recycle nutrients back into the ecosystem and keep the mudflats healthy.
Similar Species
Nassarius pulling (which is more ribbed) or Nassarius olivaceus (which is more elongated and darker). The smoothness of this fragment points toward N. dorsatus.
Beach Finding Tips
Best found at low tide on the muddy sandflats of Sandgate or Brighton. Look for small 'tracks' in the wet sand left by the snail as it moves, or near the waterline where organic debris has washed up.
Notes
Brighton beach Sandgate brisbane