Holothurian Phyllidia mimic

December 21, 1999
From: Wolfgang Seifarth

Dear Bill;

I am sending you a pic (attached) from a recent dive trip to Ellaidhoo, Ari Atoll, Maldives, where I found this small sea cucumber which obviously mimicks the phyllidiid sea slug Phyllidia varicosa. The specimen observed
had a size of about 2 cm (in a depth of about 8 m on coral rubble) indicating that it is probably a juvenile form of a holothuroid echinoderm (see mouth tentacles at the right end).

I think it is very interesting that not only flatworms but also holothuroids are mimicking sea slugs!

Merry christmas and a happy new year!



Seifarth, W., 1999 (Dec 21) Holothurian Phyllidia mimic. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1695

Dear Wolfgang,
Thanks for the best wishes and thanks for the wonderful photo.

You are right in surmising that this is a juvenile holothurian. Even more interesting is that this species, Bohadschia graeffei, changes colour from juvenile to adult. It starts life as a brightly coloured mimic of very distasteful phyllidiid nudibranchs, such as Phyllidia varicosa and P. coelestis, but when it grows larger than phyllidiids grow, it gradually changes to a camouflaged mottled white and brown colour more typical of other species of the genus Bohadschia.

There are some photos of the intermediate and adult stages in Gosliner, Behrens & Williams (1996) Coral reef Animals of the Indo-Pacific.

Bill Rudman.

Rudman, W.B., 1999 (Dec 21). Comment on Holothurian Phyllidia mimic by Wolfgang Seifarth. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1695



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