Re: more Ancula from NE Pacific

June 1, 2006
From: Jan Kocian

Concerning message #16657:

Hello Bill,
A few days ago I saw photos of Ancula on the Forum and since they were taken at a locality where I frequently dive, I could not resist to go and try to find the slug myself, since I never saw it before. In spite of very poor visibility we experiencing lately, I managed to find four individuals, at the same location, but unlike Bill Hevener's photos, two of these have white specks. Also note the infestation by parasites commonly found here on Janolus fuscus.

Locality: Langley Tire Reef, 35 feet, Washington, USA, Puget Sound, NE Pacific Ocean, 29 May 2006, artificial reef. Length: 14 mm. Photographer: Jan Kocian.

Best regards,

Kocian, J., 2006 (Jun 1) Re: more Ancula from NE Pacific. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Jan,
This is certainly a 'species' which needs some work. Your non-spotted animals clearly show the yellow lines on the tips of the gills. The two white-spotted animals seem to have a double row of lateral papillae behind the gills. Other photos of this colour form on the Forum don't have this double row, so it must be a peculiarity of these animals rather than of this colour form.

It's interesting to see that the parasitic copepods infect both colour forms. In fact I noticed the white lump in the gill region of Bill Hevener's animal and wondered if it was a parasite. Your photos certainly confirm it most surely was.

For those of you not familiar with copepod parasites in nudibranchs, have a look at the parasite page for some links. In Jan's photos, the large curved white 'sausages' are the egg sacs of crustacean parasites, the body being inside the nudibranch.

Best wishes,
Bill Rudman

Rudman, W.B., 2006 (Jun 1). Comment on Re: more Ancula from NE Pacific by Jan Kocian. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Ancula gibbosa

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