The majority of marine bioluminescent organisms are self-luminescent, meaning they have their own luciferin (Herring 2002). Many species synthesize this luciferin themselves, however, there are a few species, including the mysid Gnathophausia (Fig.6), that acquire the luciferins through their diet.
The luminescence can be released directly into the water column as chemicals or retained in cells known as photocytes (Widder 2010). More complex structures involving secondary emitters are known as photophores, as in bacteria utilising species. However, unlike the bacteria utilising species, there may be any number of photophores, located in area or the body, in a single organism (Marshall 1979). These photophores may be manipulated to modify the beam emitted e.g. the beam may be reflected, filtered or refracted.