100 things challenge - 15: Lighted animals
The world is illuminated by glowing organisms. Glow-worms and fireflies are perhaps the best-known members of a group of creatures who glow in the dark - also known as bio-luminescence, but there are many more insects, jellyfish, crustaceans, molluscs, fish, fungi and microorganisms who possess this ability.
The chemistry of the glowing is similar in all these animals. Central are the molecules known as luciferins, which emit light when they are oxidated (a similar reaction to burning, but with all the energy released as light in stead of heat). There are different luciferins, which emit light of different wavelengths, meaning we can animals glowing with different colours. Glow-worm luciferin emits green light, while the luciferin found in most marine creatures produces a blue glow. Glows in yellow and red can also be found within the animal kingdom. The glow of deep-sea fish is usually not produced by the fish itself, but by bio-luminescent bacteria they house in a special organ.
Glowing is done for a variety of reasons. Glow-worm females use it as a beacon to attract males, while glow-worm larvae seem to emit the light to warn predators they are toxic. Bio-luminescence in fungi probably serves to attract insects which disperse the spores. Anglerfish dangle a glowing lure in front of their mouth to attract prey withing striking distance!
The chemistry of the glowing is similar in all these animals. Central are the molecules known as luciferins, which emit light when they are oxidated (a similar reaction to burning, but with all the energy released as light in stead of heat). There are different luciferins, which emit light of different wavelengths, meaning we can animals glowing with different colours. Glow-worm luciferin emits green light, while the luciferin found in most marine creatures produces a blue glow. Glows in yellow and red can also be found within the animal kingdom. The glow of deep-sea fish is usually not produced by the fish itself, but by bio-luminescent bacteria they house in a special organ.
Glowing is done for a variety of reasons. Glow-worm females use it as a beacon to attract males, while glow-worm larvae seem to emit the light to warn predators they are toxic. Bio-luminescence in fungi probably serves to attract insects which disperse the spores. Anglerfish dangle a glowing lure in front of their mouth to attract prey withing striking distance!