Eubranchus rupium from Holland

September 10, 1999
From: Rob Dekker

Dear Bill,

Here are some slide scans of the aeolidacean nudibranch Eubranchus rupium (Möller, 1842) and its spawn on the hydroid Laomedea longissima, collected on 8 May 1987 at Texel, the Netherlands.

Eubranchus rupium is a northern species, reaching its southern limit in the East Atlantic along the continental North Sea coast near the Dutch/Belgian border. In the Netherlands it reproduces in winter and early spring, and is in particular abundant after severe winters. It preys exclusively upon the calyptoblastic hydroid Laomedea longissima.

I have sent you pictures of three different specimens, to illustrate the individual variability in colouration of the diverticulae of the digestive gland in body and cerata. Note also the variation in
intensity of the white and red-brown pigmentation of the skin of the body, rhinophores and cerata. You can add this species to your list of Dutch nudibranchs.

With kind regards,

Rob Dekker

Netherlands Institute for Sea Research
P.O. Box 59
1790 AB Den Burg
The Netherlands

Dekker, R., 1999 (Sep 10) Eubranchus rupium from Holland. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Rob,
This species gives us a good view of the branching of the main digestive gland ducts in the body.
Best wishes,
Bill Rudman.


Eubranchus rupium

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