Noctiluca miliaris

Noctiluca scintillans, commonly known as the sea sparkle, and also published as Noctiluca miliaris, is a free-living, 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. N. scintillans has a ventral groove that holds a flagellum, an extension of the cell wall called a tooth, and a striated tentacle involved in ingestion that projects posteriorly. The flagellum does not move the organism, so the nonmotile N. scintillans depends on regulation of its buoyancy within the water column – perhaps by controlling its cellular concentration of ions and ammonia. N. scintillans produces a string of mucus extending from the tip of the tentacle which then adheres to plankton and ascends rapidly through concentrations of its prey in the water column. N. scintillans is a heterotroph that engulfs, by phagocytosis, food which includes plankton, diatoms, other dinoflagellates, fish eggs, and bacteria. Diatoms are often found in the vacuoles within these single-celled creatures. These green nonfeeding symbioses can grow photoautotrophically for generations. Diatoms of Thalassiosira have been noted as a favored food source of these organisms. N. scintillans can be found widely distributed throughout the world, often along the coast, in estuaries, and shallow areas of the continental shelf that receive plenty of light, which promotes the growth of the phytoplankton that make up a large portion of the N. scintillans diet. Noctiluca species are unusual among dinoflagellates in appearing to have a diplontic life cycle. N. scintillans populations can exhibit high concentrations due to high concentrations of the plankton on which they feed, which are likely due to environmental conditions such as well-mixed, nutrient-rich waters, seasonal circulation, and runoff from agricultural pollution. The glow produced by N. scintillans organisms can be perceived by humans as ghostly colored glow or bloom in the water, which appears when the water is disturbed. This gives N. scintillans the popular names 'sea ghost' or 'fire of sea'.