Living organisms produce light without producing heat through a chemical reaction resulting in bioluminescence. Bioluminescence is luminescence occuring in a living organism. Bioluminescence can be found infireflies, jellyfish, and many other ocean creatures. The light emitted by ocean creatures is usually a blue or green colour because blue light travels best in water. Light from marine creatures is made in specialised organs called photophores. Inside the photophores there are two chemicals that react with each other resluting in the emission of light. These two chemicals are luciferin and luciferase. The luciferin is the chemical that actually creates the light and the luciferase is the chemical that triggers this reaction. For many marine organisms, bioluminescence is their form of survival. It is used as a warning to predetors, as a camouflage, or as a lure for prey. Bioluminescence is a beautiful phomenon of our Earth that is yet to be fully discovered.
To learn more about bioluminescence, you can watch this video: http://www.ted.com/talks/edith_widder_the_weird_and_wonderful_world_of_bioluminescence.html
