Question of the month

Vultures of the snail world

Can you please identify this small marine snail that I spotted while photographing soldier crabs on the flats at Brighton. It was in a shallow pool near a little hermit crab.

Answer

A Channelled Dog Whelk (Nassarius dorsatus) with its siphon extended A Coronate Dog Whelk (Nassarius coronatus) with its foot clearly visible Your snail is a Channelled Dog Whelk (Nassarius dorsatus). This species is common in Moreton Bay and is often seen scavenging on decaying crabs and fish.

The dog whelks are marine snails within the family Nassariidae, a group that is nested within the largest class of molluscs, Gastropoda. Other members of this class include cowries, cone snails, tritons, periwinkles and sea slugs. Moreton Bay alone contains over 1000 recorded species of gastropods!

Dog whelks have a head with a pair of eyes and fleshy tentacles, a large foot and a shell which contains the visceral mass. In many snails, including the dog whelks, the opening to the shell can be sealed by a door-like structure (called an ‘operculum’ which is attached to the foot) when the animal withdraws inside. Like most other snails they have another weapon in their armoury, a rasp-like ‘tongue’ of teeth which is used to tear food to small pieces for ingesting.

These photographs show two species of dog whelk using their extended siphon. The snail draws in water to ‘taste’ for signs of food. This olfactory sense helps it to locate its next meal. Dog whelks can be vigorous scavengers and often do so communally. They play an important role in the marine areas they inhabit cleaning up decaying matter.

The name ‘dog’ whelk may derive from its tendency to ‘sniff out’ food with the long proboscis or it may express disapproval as these snails were considered not as good to eat as other molluscs.

 


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