Noctiluca scintillans, commonly known as the sea sparkle, and also published as Noctiluca miliaris, is a free-living, nonparasitic, marine-dwelling species of dinoflagellate that exhibits bioluminescence when disturbed (popularly known as mareel). Its bioluminescence is produced throughout the cytoplasm of this single-celled protist, by a luciferin-luciferase reaction in thousands of spherically shaped organelles, called scintillons. Nonluminescent populations within the genus Noctiluca lack these scintillons.