The ocean contains a much greater diversity of bioluminescent organisms than does the remainder of the global environment. These organisms range from single-celled bacteria and dinoflagellates to sharks and squid more than a metre in length and on to siphonophores tens of metres long.
Luminous species are present at all depths.
The light output of individual organisms varies markedly between species and there is no simple correlation with their size. Holothurians may be important close to the seabed. The distribution patterns of many luminous organisms in the upper 1000m are subject to diel vertical migration and the epipelagic populations at night include many of the daytime deep-water species. Despite our knowledge of the populations, the causes of some of the more spectacular marine bioluminescent phenomena are still not understood. Return to SD Workshop Page .