Cuthona sp. 2.

Family: Tergipedidae

Authorship details
Rudman, W.B., 1999 (January 6) Cuthona sp. 2. [In] Sea Slug Forum. Australian Museum, Sydney. Available from

Related messages

Yet another nudibranch

January 6, 1999
From: Eirik Mack Eilertsen

Thank you very much for the quick and, as far as I can tell, correct identification of the nudibranchs in my reef tank. I seem to have another species of nudibranchs in my tank as well. I'm sending you a picture of the animal and one of the egg containers. One of these species seem to feed on my zooanthids and possibly my soft corals and I'm still trying to find out which one.
The colors got a bit bleak in my scanner, but the cetae should be dark brown with green specs that seem to flouresce under the right light. Furthermore, the cetae are arranged in small vertical rows along the sides of the animal. Note also the very long and thin second pair of tentacles. The animals are fairly small (some 15 mm) with ring shaped or spiraling egg containers some 5 mm in diameter.


Eilertsen. E.M., 1999 (Jan 6) Yet another nudibranch. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Eirik,
I'm afraid your second animal is not so simple. From your drawing and description, I am fairly sure it is an aeolid of the genus Cuthona. However there are many described species and probably as many undescribed species in the tropics. Most feed on hydroids, but one feeds exclusively on the hard coral Porites. There is another genus Aeolidiopsis which feeds on Palythoa but it doesn't look like your animal. I suspect your animal got caught up in the collecting. Its hard to know whether it had grown since you got it, but as it is laying eggs I suspect it has found something edible.
Best wishes,
Bill Rudman.

Rudman, W.B., 1999 (Jan 6). Comment on Yet another nudibranch by Eirik Mack Eilertsen. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from