A common luminescent animal is the firefly, or otherwise known as the lightning bug. There are over 2000 species in the world, and over 125 in the U.S. and Canada. The larvae of most species of firefly also glow. The light produced by fireflies is produced by a reaction between the chemical luciferin and the enzyme luciferinase in the presence of oxygen, ATP, and magnesium ions. These beetles can control the flashes of light by controlling the supply of oxygen to the light-producing organs.
Fireflies use their lights to attract mates.
Every firefly species has its own flash pattern. The male Photinus pyralis, the most common species, flashes his yellowish light for a half a second while ascending and repeats about every seven seconds. The flightless females respond to these flashes from the ground or vegetation. The male knows a female of his species by the response time of her flash. The male then has to reach the female before another male that saw the flash, does.