The glow-in-the-dark entities make use of variations on a chemical reaction which involves three chief components, namely luciferase that helps oxygen molecule to bind to an organic molecule which serves as a third ingredient known as luciferin. The high-energy molecules that are created by the reaction liberate energy in the form of light.
Bioluminescence is the emission and production of light by living entities and is a form of chemiluminescence. This process is mainly observed in the vastest habitat on the planet – the deep sea. It widely occurs in marine vertebrates and invertebrates and also in some fungi, microbes, bioluminescent bacteria and some terrestrial invertebrates such as fireflies.