Open brain coral fluorescing green in blue light

Fluorescence in corals and anemones:

Many corals and anemones exhibit brilliant green fluorescence under blue light, but few fluoresce as brightly as the open brain coral in our coral reef aquarium. This bright green color is caused by fluorescent green proteins in the coral's tissues. The function of these proteins is not completely understood, but one likely hypothesis is that the proteins serve as a sort of protective sunscreen. By absorbing harmful ultraviolet light and re-emitting this high energy radiation as harmless visible light, the proteins protect the corals from "sunburn".

Why the blue lights over the tanks?

• The blue end of the spectrum penetrates deeper into the water than other wavelengths, so blue light predominates even at moderate depths. Accordingly, the symbiotic algae that live within and feed the corals, anemones, and giant clams use blue light more efficiently than other colors.
• In our aquaria, the blue lights come on an hour before, and go off an hour after the white, metal halide lights. This simulates natural dawn and dusk periods, which is beneficial to the organisms in the aquaria.

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