From them a faint bioluminescence (often called phosphorescence) occurs. The luciferin-luciferase reaction responsible for the bioluminescence is pH sensitive. Fluorescence is often confused with the following forms of biotic light, bioluminescence and biophosphorescence. This fluorescence occurs as a by-product of bioluminescence from these same photophores. The genetics of firefly bioluminescence, focusing on luciferase, has been reviewed by John Day. In fireflies, an enzyme in the abdomen catalyzes a reaction that results in bioluminescence. Light production in fireflies is due to a type of chemical reaction called bioluminescence. Crown jellyfish are able to make light through bioluminescence. Certain bacteria are able to use quorum sensing to regulate bioluminescence, nitrogen fixation and sporulation. One explanation for the role of bacterial bioluminescence is from the biochemical aspect. The organ that is responsible for the emission of bioluminescence is known as photophores. Thus, the jellyfish may change the color of its bioluminescence with depth. This species is capable of producing light via bioluminescence in its mycelium. The physiological and ecological function of fungal bioluminescence has not been established with certainty. No correlation of fungal bioluminescence with cell structure has been found.