Phyllodesmium from Japan

January 18, 2001
From: Satoru Hori

Dear Bill

My friend, Matsuura, found this sea slug in Yokosuka, Japan. He took it in his fish tank. After a few weeks, he noticed this sea slug ate soft coral in his tank. Before he returned it to the sea, I took this photo.

Its length is about 15mm. Rhinophores are smooth. Ceratas are not smooth. Some ceratas are located just at the side of the rhinophores.

Could you identify it for me?

Thank you.
Satoru Hori

Hori, S. , 2001 (Jan 18) Phyllodesmium from Japan. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Satoru,
Thanks for the photo. This is a species of Phyllodesmium, and most probably it is Phyllodesmium hyalinum which feeds on soft corals such as Xenia. P. hyalinum and a another similar species Phyllodesmium crypticum have bumps on the cerata as in Matsuura's photo. The cerata therefore look very like the tentacles of the Xenia polyp so that it is very difficult to find when it is feeding. Have a look at the photo of Xenia and its tentacles elsewhere in the Forum.

Best wishes,
Bill Rudman

Rudman, W.B., 2001 (Jan 18). Comment on Phyllodesmium from Japan by Satoru Hori . [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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