Platydoris formosa? - egg ribbon

June 27, 2002
From: Todd Garthwaite

Hi Bill.
I came across a very large egg ribbon, that I thought might be from a Platydoris formosa, (Neville Coleman has a similar picture of a nudibranch egg mass on pg. 60 of his book 1001 Nudibranchs). With its distinct reddish color, I also thought it might be from a Hexabranchus sanguineus. I've never seen an egg mass like this one before.
Any ideas?

Site: "Jin-Sha Wan" (["Golden Sand Bay"], N.E. Coast, Taipei County, Taiwan)
Date: 08 June 2002
Time: 09:43am
Depth: 7 meters
Temp: 25 degrees C.
Size: Approx. 150 + mm (semi-coiled)

Stay golden.
Best wishes always, (and many thanks),
Todd Garthwaite
(Taipei, Taiwan)

Garthwaite, T., 2002 (Jun 27) Platydoris formosa? - egg ribbon. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Todd,
We know so little about egg masses that it is always difficult to identify them except in very special circumstances. This looks quite like the egg ribbon of Hexabranchus but we have to be careful we don't start making up myths. Unless we actually see an animal laying an egg ribbon, it is almost impossible to safely identify it unless it has a very unique shape and is on the special food of a particular nudibranch. For example I am fairly confident in identifying some species of Rostanga but for the vast majority of nudibranchs it is a very risky business.
Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Jun 27). Comment on Platydoris formosa? - egg ribbon by Todd Garthwaite. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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