April 14, 2010
From: Dominique Horst
This should be Tritonia striata. It is crawling on the sponge Aplysina aerophoba.
Any idea on what this species is feeding?
Locality: Banyuls, 7m, France, Mediterranean sea, 28 March 2010. Length: 12 mm. Photographer: Dominique Horst.
Many thanks in advance,
Horst, D., 2010 (Apr 14) Tritonia striata from the French Mediterranean. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/23422
Tritoniids feed on soft corals and their close relatives so its presence on the sponge colony is not significant - just one of thsoe traps we can fall into when looking for signs of feeding.
Tritonia striata has not often been reported so we don't know much about its biology. It has been reported to feed on the soft coral Paralcyonium elegans but I guess more work will need to be done to confirm whether it feeds on a variety of soft corals or is retsricted to one or a very few species.
I have added a few close-ups from your excellent photos showing the details of the rhinophores and gills.