Bioluminescence is the production and emission of light by living organisms. In the chemical reaction process of bioluminescence, the enzyme luciferase catalyzes the oxidation of the pigment luciferin, light is emitted during the reaction. Bioluminescence is produced by organisms for the following purposes: counter-illumination camouflage, attraction for mates or preys, illumination, defence, warning and communication. In Hong Kong, this biological process can be observed on fireflies, in some fungi (Hohenbuehelia serotina and Panellus stipticus etc.) and Noctiluca scintillans (dinoflagellates).