Science
How does bioluminescence work?
Bioluminescence is light produced by living things, like fireflies and deep-sea creatures, through a chemical reaction inside their bodies. A light-emitting molecule reacts with oxygen, releasing energy almost entirely as light rather than heat.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how bioluminescence works.
Step by step
- 1A molecule called luciferin reacts with oxygen, helped by an enzyme (luciferase).
- 2The reaction releases energy as 'cold light' — very little is wasted as heat.
- 3Fireflies, many deep-sea fish, plankton, fungi, and some bacteria can do it.
- 4Animals use it to attract mates, lure prey, or scare off predators.
- 5In the dark deep ocean, it's one of the most common forms of communication.
Frequently asked questions
- How do fireflies make light?
- Inside their bodies, luciferin reacts with oxygen, controlled by an enzyme, producing flashes of nearly heatless light used mainly to attract mates.
- Why is it called 'cold light'?
- Because almost all the energy becomes light rather than heat — unlike a bulb, the reaction barely warms up, which makes it extremely efficient.
- Why do deep-sea animals glow?
- In the dark deep ocean, glowing helps them find mates, lure or spot prey, and confuse predators — light is a vital tool where sunlight never reaches.