Deep-diving fish have a problem: The only light that penetrates their watery environment is blue and green - hardly enough of a palette for flashy color patterns.
Now, a new study reveals these fishes' solution: In deep water, fish simply fluoresce more - a technique that allows them to convert blue-green light into red light.
"Under light conditions that do not provide the full spectrum - the full rainbow of colors that we have at the surface - it's really nice to have fluorescence, because you can still have those missing colors," said study researcher Nico Michiels, a professor at the University of Tüebingen in Germany. (Gallery of Glowing Sea Creatures)
Most color pigments work by absorbing some portions of the light spectrum and bouncing the rest back. A yellow flower, for example, absorbs blues, greens and reds, and sends yellow shooting back toward the eye of the observer.
Fluorescence is slightly different. The molecules responsible absorb one wavelength of light and then emit another, longer wavelength. This occurs through a process of excitation, in which the molecule absorbs light energy and then emits a lower-energy wavelength than the one it absorbed, in order to return to its resting state.