Cuthona nana
(Alder & Hancock, 1842)

Family: Tergipedidae


North Atlantic, as far south in Europe as France, & New Hampshire in North America. Very similar species Cuthona divae (Marcus, 1961) in northeast Pacific.


In hydroid colony, note egg masses. Plompe toren, de Oosterschelde, the Netherlands. PHOTO: Peter H. van Bragt

Grows to about 30mm. It feeds predominately on the hydroid Hydractinia echinata, which is often, but not exclusively, found attached to shells inhabited by hermit crabs.

• Thompson, T.E. & Brown, G.H. (1984) Biology of Opisthobranch Molluscs, Vol 2. Ray Society: London.

Related messages

Cuthona nana in the Netherlands

August 28, 1999
From: Peter H. van Bragt

Dear Bill,

Here is a photo of Cuthona nana to add to the Netherlands' List.

Location: Plompe toren, de Oosterschelde, the Netherlands

With best regards

Peter H. van Bragt

van Bragt, P.H., 1999 (Aug 28) Cuthona nana in the Netherlands. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Peter,
I always used to think Cuthona nana was only found on hydroids growing on the shells of Nassarius. There is a similar association with hydroids living on living Nassarius here in Australia. I don't know how many snails I have upset while diligently, but fruitlessly, looking for a similar Cuthona down here, before I realised I should be looking at hermit crab inhabited shells.
Best wishes,
Bill Rudman.