A light in the darkCarlos Taboada et al.By Sam WongShine on you crazy frog. The polka-dot tree frog is the first amphibian known to be naturally fluorescent. Fluorescence, which happens when a substance absorbs light at one wavelength and emits it at a longer one, is known to occur in some parrots and sea turtles, and a wide variety of fish. The polka-dot...