Well, I dont know about light/photosynthesis capacity with regards to color in animals... But, dont lighter colors reflect light and darker colors absorb more? Is that why solar panels are black and not white? I am under the impression, at least with some anemones, that the lighter colored ones may have lost zoxanthalae (spelling?)(symbiotic material that photosynthesises and creates most of the energy for anemones), which can mean that they are not processing enough light to sustain life, hence the color/photosynthesis question. I would like to hear some other viewpoints, as this is a great question, could lead to a total reconfiguration of some systems :o