Re: Flabellina lineata from France

March 6, 2008
From: Dominique Horst

Concerning message #3003:

Hello Bill,

This should be Flabellina lineata.
It's more than two years since I first found this species. In my last two dives a friend of mine shot two different individuals which have a very different colour.
As with Janolus cristatus, could this colour variation be explained by what the slug feed on?

Locality: Antibes Cape, 14m, France, Mediterranean sea, 03 March 2008. Length: 20mm. Photographer: Dominique Horst (upper photo), Yves Louis (lower photo).

Kind regards,

Horst, D., 2008 (Mar 6) Re: Flabellina lineata from France. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Dom,

Yes the colour difference is almost certainly food related. In aeolids the 'food processing' organ or digestive gland is found not in the body cavity but up in the branches of the cerata, and the colour of the digestive gland quickly takes on the colour of the food it is processing. If you look at the Favorinus japonicus Fact Sheet  you will see an animal in the process of changing colour as it moves from pink to green food. In the close-up alongside you can see the organs in the body of the Flabellina are pale pink while those in the cerata are red. This reflects the different organs - in the body cavity the tissue you can see is almost exclusively gonads -ovary, testes - whicle in the cerata it is digestive gland and ingested food.

Best wishes,
Bill Rudman

Rudman, W.B., 2008 (Mar 6). Comment on Re: Flabellina lineata from France by Dominique Horst. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from


Flabellina lineata

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