Madrella ferruginosa from Japan

November 14, 2003
From: Yukari Sato

Hello Dr.Rudman,
I have found this animal at Izu, Japan.
I think this belong to the genus Madrella, but I do not know the species name.

Loc:Futou, Suruga bay west coast of Izu peninsula,Japan

Best regards,
Yukari Sato

Dear Yukari,
This is indeed a Madrella, almost certainly Madrella ferruginosa. It is very difficult to photograph in situ as it is so well camouflaged against its bryozoan prey. An interesting feature of your animal are the white sausage-shaped objects on the back of the animal. In the close-up alongside you can see that they are a collection of tiny spheres and are in fact the egg masses of a parasitic copepod which must have taken up residence on the Madrella
Best wishes
Bill Rudman

Rudman, W.B., 2003 (Nov 14). Comment on Madrella ferruginosa from Japan by Yukari Sato. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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