Re: Feeding observations on Chromodoris binza

Dear Linda,

Thanks very much. Your photo actually clarifies an 'uncertain feeling' I had with Anne's photos because one purple colony in her photo didn't look quite right. Your photo clearly shows there are two quite unrelated purple sponges living side by side. In your whole photo [top right] you will see that the Chromodoris is on a dark purple sponge with an irregular honeycomb pattern. That is Chelonaplysilla sp., the food of C. binza. Most of the rest of the background is covered with a lighter, almost watery-coloured, purple sponge, which in the close-up [middle right photo] can be seen to have a quite different structure. It has pale tubercles all over from which radiate fibres in a star-like pattern. This is a dysideid sponge, perhaps a species of Dysidea, which coincidentally is the preferred food of species of the related genus Hypselodoris. Interestingly in both Anne's and Linda's photos the C. binza are showing an interest only in the Chelonaplysilla colonies. This is a good example of how easy it is to make a mistake when studying food preferences.

Best wishes,
Bill Rudman