Sea anemone fluorescing underwater

Sea anemone fluorescing yellow underwater, photographed at night using blue coloured flashlight and a yellow filter. An anemone fish hides amongst its tentacles. Blue light excites pigments within some underwater organisms causing them to emit a fluorescent glow. The sea anemone harbours symbiotic algae which require light to photosynthesize, producing nutrients which sustain it. It is thought that in shallower waters, the fluorescent pigments in such organisms act as a sunscreen that prevents too much ultraviolet light damaging the algae. In deeper waters and lower light levels, it is thought that the fluorescent pigments absorb ultraviolet light and emit it at a wavelength which promotes photosynthesis in the algae. Photographed in the Lembeh Strait, North Sulawesi, Indonesia.