The Noctilucales are a peculiar order of marine dinoflagellates. These differ from most other groups in that the mature cell is diploid and its nucleus does not show a dinokaryotic organization. These cells are very large, from 1 to 2 mm in diameter, and are full of large buoyant vacuoles. They lack chloroplasts, though a few have symbiotic green algae within the vacuoles, and feed on other plankton, with a special tentacle involved in ingestion. During sexual reproduction, gametes are produced which resemble more typical athecate dinoflagellates and have dinokaryotic nuclei. Evidence suggests that the Noctilucales diverged from most other dinoflagellates early on, and they are generally placed in their own class. The best known member is Noctiluca scintillans, which is bioluminescent when disturbed, and can sometimes be seen as flickering lights on the ocean at night.