Semi-Intrinsic Luminescence in Marine Organisms

Light emission is widespread in the oceans, with over three quarters of all observed marine species exhibiting bioluminescence. Several organisms such as the copepod Metridia pacifica and the ostracod Vargula hilgendorfii have been proven to synthesise their luciferin and luciferase to facilitate light emission. However, many luminescent species lack the capability to do this and instead it is possible that they acquire some of the components for their luminescence through predation or filter feeding on organisms that produce luciferins or precursors to these molecules. This has resulted in many organisms using certain luciferins, such as coelenterazine, as their substrate without possessing a clear mechanism to synthesise these. This chapter will review several examples of these semi-intrinsic luminescent systems and how the substrates and enzymes can be obtained for these reactions. Moreover, it will look at why particular luciferins, such as coelenterazine, are more widespread and utilised in this manner compared to other substrates.