Feeding observations on Chromodoris binza

Dear Anne,

Thanks for this great set of photos. There is no doubt in my mind that they are feeding on this purple sponge. More importantly, I am 99% sure it is the same sponge as your Chromodoris clenchi was eating in your message #20835.

I think the sponge is a species of Chelonaplysilla. Interestingly in the Indo-West Pacific Chelonaplysilla violacea is the preferred food of 15 or more chromodorid species most of which have purple in their colour pattern.
Perhaps the purple pigment in these chromodorids is derived from the sponge? If you feel the sponge it has a rough texture, because it
incorporates small sand grains in its tissue.

I will of course need to check the identity of the sponge with an expert. Also of interest is that C. binza and C. clenchi are two of a group of Atlantic species some of which may be forms of one species [see message #3157]. In commenting on that message I said 'It would be interesting to get some information on their food preferences and the shape of their egg masses'. Your two messages are a valuable couple of steps in building up information on these colourful, if problematic, species.

Note added 19 May 2009: The purple sponge in the upper corners of the lower photo [and lower close-up in middle left photo] are a species of Dysidea, which is living alongside the Chelonaplysilla. See Linda Ianniello's message [# 22482] for further photos and discussion.

Best wishes,
Bill Rudman