Limpet-like slug from New South Wales

February 22, 2010
From: Sam Rodely

I wondered if i could get some help identifying this interesting slug I found while working my family's oyster leases on the NSW far south coast. It seems to be mimicking a limpet, both in shape and pattern.

Locality: Nelson Lagoon, intertidal , NSW, Australia, 10 February 2010, on oyster farm post. Length: smallest 14mm largest 20mm. Photographer: Sam Rodely.


Rodely, S.J., 2010 (Feb 22) Limpet-like slug from New South Wales. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Sam,

These are definitely slugs, and as they live in the sea you would be right to think they are 'seaslugs' but in fact they are much more closely related to land slugs and land snails than they are to opisthobranchs and nudibranchs which we normally called 'sea slugs'.

They belong in the family Onchidiidae, and like land slugs and snails, they have a 'lung' and breathe air. In live animals you will see that like land slugs and snails their eyes are found at the tips of long eye stalks while in true 'sea slugs' the eyes are usually embedded in the skin.

Onchidiids are quite common in intertidal locations and different species are found in mangroves swamps and rocky shores. In some parts of the world they can grow extremely large [up to 70 mm long]. Have a look at the Fact Sheet and older messages attached to it for further information

Best wishes,
Bill Rudman

Rudman, W.B., 2010 (Feb 22). Comment on Limpet-like slug from New South Wales by Sam Rodely. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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