Egg-laying Trapania benni from S.E. Australia

January 17, 2002
From: John Chuk

Dear Bill,
Here are images of an egg-laying specimen of Trapania benni and the egg ribbon. The specimen was found on a dive at Portsea Pier, Victoria, Australia on 30/Nov/2001. It measured 11mm in length and was found at a depth of 4m on a pier pylon.

I spotted the egg mass first and had to search to find the nudibranch responsible. It was very well disguised against the red alga it was on. After observing this specimen for about five minutes I discovered that there was a second specimen present and it too was egg laying. The egg ribbon was wrapped around a red alga and the stems of a small hydroid colony.

Both specimens were observed on or near the egg ribbon for the next three days but when I dived the site ten days later there was no sign of either the nudibranchs or their egg ribbon.

Best wishes,

Chuk, J., 2002 (Jan 17) Egg-laying Trapania benni from S.E. Australia. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks John,
I don't recall seeing this animal laying eggs before. I am not sure from the photos abut the shape of the egg mass. Is it a flat ribbon, like most dorids, or is it cylindrical?
Best wishes,
Bill Rudman


Trapania benni

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