Spanish Dancer with white eggs?

April 6, 2000
From: Jan Reyniers

Hello ,

After visiting your webside I have a question about the Spanish Dancer eggs.

On my last trip to Egypt, [Ras Mohammed, Sinai], I found some eggs of a Spanish Dancer?? The only problem with these eggs is
that they are WHITE. Can you give me more information , or is this normal?

I've dived there for more than 300 times and this was the first time I saw them in this white colour. Or are they from another animal. The Depth was 18 meter and the egg-ribbon was about 30 cm in diameter.

Greetings,
Jan Reyniers

jan.reyniers@pandora.be

Reyniers, J., 2000 (Apr 6) Spanish Dancer with white eggs?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/2217

Dear Jan,
From my own experience and from the literature (Gohar & Soliman - Red Sea; Francis - West Pacific), Hexabranchus sanguineus, the Spanish Dancer, has an egg ribbon which is bright pinkish red when laid, and changes to a reddish brown colour before hatching.

As you didn't see who produced the eggs and suggestion of mine is going to be a bit of a guess. My bet is that they are probably the eggs of Pleurobranchus forskalii. There is a photo of a section of its egg mass in the Forum. Apart from the similarity in shape, there are not many opisthobranchs large enough to produce an egg ribbon of 30cm diameter. I have seen shallow lagoons in Tanzania festooned with masses of P. forskalii produced by dense aggregations or assemblies of breeding adults all about 10cm long. Although the egg ribbons were often tangled, some isolated ones were more than 10cm in diameter. As Pleurobranchus forskalii can grow to about 30cm I assume it could produce an egg ribbon of similar diameter.

But I must warn you this is only an educated guess. I would welcome any more interesting finds you would like to share with us.

Best wishes,
Bill Rudman.

References:
•Francis,MP (1980) Habitat, food and reproductive activity of the nudibranch Hexabranchus sanguineus on Tongatapu Island. The Veliger 22(3): 252-258. (Figs 1-4)
•Gohar,HAF; Soliman,GN (1963) The biology and development of Hexabranchus sanguineus (Ruppell & Leuckart) (Gastropoda, Nudibranchiata). Publications of the Marine Biological Station, Al-Ghardaqa, Egypt, 12: 219-247.

Rudman, W.B., 2000 (Apr 6). Comment on Spanish Dancer with white eggs? by Jan Reyniers. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/2217

Factsheet

Pleurobranchus forskalii

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