Is this poisonous? I think i was stung.

May 5, 2006
From: Leigh Maulson

I just found this guy in my planted aquarium. I'm asuming its some sort of pregnant nudibranch.

It's the size of a golf ball. when I touch it, 5 or six of the petals stuck to my finger (engulfed it, i could hardly get them off. they were very very sticky.) I had to wash my hands a few time to remove the residue. The petals that stuck to my finger, seem to move on their own, I'm assuming its a mother :)

To the point, can anybody id this critter? and is it poisonous? since I've touched it my knuckle is a little stiff, and my finger feels wierd. not painful, not ichy, just weird. theres no swelling and no marks.
but i am a little (very little) concerned. thanks.

I cant belive how many nudi's i've found in my planted aquarium since its been set up, however this one truly is a very cool critter.

Leigh Maulson

Maulson, L., 2006 (May 5) Is this poisonous? I think i was stung.. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Leigh,
Sorry I didn't reply immediately but I realised you were in no danger from your encounter with your slug. You were 'glued' rather than stung.

By coincidence I am posting a message about the same animal, Polybranchia orientalis, from the Red Sea [message #16492]. As I mention there, this species has the habit of dropping off lots of its leaf-like cerata when it is disturbed. This is a defensive behaviour. When it is nudged or mouthed by a fish or crab, these cerata exude a very sticky substance - which you have experienced - and at the same time drop off the animal and begin wiggling. If you are a fish and suddenly have your mouth and cheeks covered in sticky wiggling objects I guess you loose interest in the animal you were originally investigating.

So that explains your wiggling 'babies' and the stickiness on your fingers. Dropping off parts of your body like this is called autotomy. Have a look at the autotomy Fact Sheet for more examples of this interesting behaviour.

Best wishes,
Bill Rudman

Rudman, W.B., 2006 (May 5). Comment on Is this poisonous? I think i was stung. by Leigh Maulson. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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