Defensive allomones in nudibranchs

June 6, 1999
From: Dan Sanchez

I am attempting to find information regarding the ability of nudibranchs to sequester secondary compounds from other organisms for use as allomones. What types of organisms do they get these from, how do they use them, why are their bodies able to recognize them as not being foreign, and which nudibranchs can do this?

Dan Sanchez

Dear Dan,
Perhaps first I should define allomone for anyone not sure of its meaning. Its basically refers to a chemical secreted or released by an organism which cause a specific response when detected by an organism of a different species.

Have a look at Opisthobranch Defence Mechanisms which gives you a list of pages with relevant information. In particular, the Sea Hares - Chemical Defence is a bibliography of relevant papers, not only on Sea Hares but other opisthobranchs as well. One paper you should be able to obtain is Avila, 1995 which is an excellent review article. When you look at any of the pages don't forget to look at the messages and answers at the bottom of each page. They usually contain a lot more information.

Probably the most spectacular example of allomone use is found in the Chromodorididae, where all species concentrate chemicals obtained from the sponges they feed on in special glands around the mantle edge. In southeastern Australia many species have evolved a red-spotted colour pattern in a great geographic display of defensive mimicry. I have recently posted a group of pages illustrated some of these red-spotted species (message 1, message 2).

Other groups of similarly coloured species are found elsewhere, the Mediterranean being well-known for a series of blue species with yellow markings.

Another sponge-feeding dorid family with particularly nasty chemical defence are the Phyllidiidae. Have a look at the Mimicry page for a good example.

Other nudibranchs which don't feed on sponges also use chemical defence. Two quite unrelated feeders on soft-corals also harbour chemicals retained from their soft-coral food. Have a look at the information on the aeolid genus Phyllodesmium (Aeolid Ceras, Phyllodesmium longicirrum and Autotomy). I haven't got much specifically on the arminids, which also sequester chemicals from soft-corals, but have a look at the Dendronephthya-feeding page for an example.

I hope this will give you some help,
and don't forget to look at the messages below yours on this page.
Best wishes,
Bill Rudman.

Rudman, W.B., 1999 (Jun 6). Comment on Defensive allomones in nudibranchs by Dan Sanchez. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Defensive glands

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