Do you know the scene from Pixar's Finding Nemo, when Dory and Marlin get the mask stuck on the face of the giant fish which lights up or have you you ever heard of the glow worm?
This mechanism of 'lighting up' and 'glowing' is called bio-luminescence and is rife in the depths of many an ocean and in our skies. Not only are the lights used for attracting prey but it is also thought to prevent the predator from becoming prey.
Bio-luminescence unlike normal luminescence is a form of cold light emission, where less than 1/5 of the light energy produces heat. A vast majority of deep-sea creatures have this ability to illuminate themselves in the blue and green spectrum as it is these wavelengths which are able to travel through the water most effectively. in comparison non-marine bio-luminescence is less widespread with the most known kinds belonging to the glow worm and the firefly.
Many organism have been adapted to 'light up' for several different purposes: counter illumination camouflage (where the organism matches the overhead light), mimicry, the attraction of mates, distraction of a predator, repulsion, communicative purposes and for navigational reasons.
Scientists now, are trying to find a way to harness bio-luminescence and use it in the biotechnological field; with the possibly of the creation of trees which glow in the dark, reducing the need for overhead streetlamps, or Christmas trees which do not require lights, thus helping to decrease the number of fires related to electrical faults.
Just remember humans are not the only organism with all their lights blazing!
Explorer Fact: in Europe dried fish skins were used before the invention of the Davy safety lamp, as they would give off a weak glow.