Aeolid firing its nematocysts?

January 29, 2002
From: Jean-Pierre Bielecki


Hi Bill
Do you think that it is possible for an Aeolid to fire its nematocysts? Here are some photos of Facelina dubia, with maybe the answer. After I disturbed it, this one expelled, as a harpoon what I think to be his nematocysts. Could you please give me your thoughts about this.
Best regards
Jean-Pierre

bielecki.jeanpierre@free.fr

Bielecki, Jean-Pierre, 2002 (Jan 29) Aeolid firing its nematocysts?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6104

Dear Jean-Pierre,
To be on the safe side can someone confirm the identity of the aeolid please? It certainly looks like Facelina dubia but I am no expert on this fauna.

To your question about whether the lower photos show the aeolid firing its nematocysts - no I don't think they do. The brown object is not something being expelled from the ceras, but something that is grabbing the tip. The individual nematocysts in the cnidosac are microscopic and are diffcult to see with the naked eye. What I think these brown things are are specialised spines from a sea urchin [Echinoidea] which are called pedicellaria. Most sea urchins have small pedicellaria which are armed with 'parrot's beak'- like jaws at their tip. They are used to keep the echinoid's shell clean from organisms which would otherwise settle on the shell and smother it. In some species, the pedicellaria have become very large relative to the size of the spines and in one Indo-Pacific genus, Toxopneustes, the true spines are very small and the whole shell or test is covered with poisonous pedicellaria. I am not familiar with the Mediterranean fauna but I see in Ocana Martin et al.(2000) that at least two Mediterranean echinoids - Arbacia and Sphaerechinus have large pedicellaria like those hanging on to the cerata of your aeolid.

This is a nice photo of Facelina dubia. Could I have some locality details please?
Best wishes,
Bill Rudman

Rudman, W.B., 2002 (Jan 29). Comment on Aeolid firing its nematocysts? by Jean-Pierre Bielecki. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/6104

Factsheet

Facelina dubia

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