What does my mystery slug eat?

July 15, 1999
From: Joel R.

Recently, I bought a purple sea slug ( with a single white band bordering the body, yellow gills, and "horns") at a local pet store in California (U.S.A.)
Since I don't have a photograph of it as of this moment, I have included in this message a jpg (which I drew using photoshop) of the slug.
I was wondering if you could help me identify:

1. what species it is?

2. (my main question) what it primarily eats?

Unfortunately, I have no idea where this particular species comes from; I hope the illustration helps, however. Thank you very much for your time.

Joel R.


Ruidera, J., 1999 (Jul 15) What does my mystery slug eat?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1070

Dear Joel,
The slug is instantly recognisable from your great effort with Photoshop. If you have a look at the page on Hypselodoris bullocki you will find an almost identical animal in Photo E. At the moment we are considering this group of differently coloured animals to be colour forms of the one species, Hypselodoris bullocki, mainly because we can't find any anatomical differences which could be used to consider them different species.

I'm afraid there is not much likelihood of you finding a sponge that it will eat as most chromodorids are fairly choosy in their diets. I have a photo of one colour form feeding on a species of the sponge Dysidea. Other chromodorids feed on species of Aplysilla. There are species off both Dysidea and Aplysilla in Californian waters. You will need to find someone in California who can help you with sponge identifications, but it may be worth seeing if your nudibranch will eat them. I remember some years ago the endemic species of Rostanga in New Zealand, by some freak of biochemistry, was found to prefer an introduced sponge from Europe over all the native New Zealand sponges that it normally fed on.

Best wishes,
Bill Rudman.

Rudman, W.B., 1999 (Jul 15). Comment on What does my mystery slug eat? by Joel R.. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/1070

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