Thorunna australis on possible food, Mayotte Island

March 11, 2010
From: Matthias Deuss

Dear Bill,

I found this little Thorunna australis under a dead Acropora coral. You may find its favorite food among all the sponges it's crawling on, though I can't spot any trace of feeding on these.

Locality: Bandrele inner reef, 2 metres, Mayotte Island, Comoros, Indian Ocean, 28 December 2009, Living coral area. Length: 10 mm. Photographer: Matthias Deuss.

Best wishes,

Matthias Deuss

Deuss, M., 2010 (Mar 11) Thorunna australis on possible food, Mayotte Island. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Matthias,

These slugs don't make it easy for us. Sponge colonies in crevices are often mishapen and difficult to identify. In this case I think there is more than one species of sponge present and I suspect the whitish network on which the slug is crawling is not its food sponge but possibly a calcareous sponge. However on either side of your photo are bits of perhaps the same colony of another species, which could well be a species of Dysidea. We have two records on the Forum [#22474; #1201] showing this species feeding on a nondescript encrusting dysideid. Your message could represent a third record.

Best wishes,
Bill Rudman

Rudman, W.B., 2010 (Mar 11). Comment on Thorunna australis on possible food, Mayotte Island by Matthias Deuss. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Thorunna australis

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