These cells are very large, from 0.2 to 2 millimetres in diameter, and are filled with large buoyant
vacuoles. Some may contain symbiotic
green algae, but there are no
chloroplasts. Instead, they feed on other
plankton, and there is usually a special flagellum involved in ingestion.
Noctilucales reproduce mainly by fission, but
sexual reproduction also occurs. Each cell produces numerous gametes, which resemble more typical athecate dinoflagellates and have the dinokaryotic nuclei. Evidence suggests that they diverged from most other dinoflagellates early on, and they are generally placed in their own class.
The most common species is Noctiluca scintillans, also called N. miliaris. Blooms of this species are red-orange and can be
bioluminescent when disturbed,[4] as are various other dinoflagellates, and large blooms can sometimes be seen as flickering lights on the ocean, known as the
milky seas effect.