Luminousbeings,creatureswiththeirowninternallight,enchantandastonishus.Anyonewhohasseenafireflyoraglow-wormcannothelpbutfallundertheirspell.Theseaatnightsparklesasmillionsofluminousplanktonrevealtheshapesofdolphinsinatrulymagicallightshow.Butwhydoanimalsproducelivinglight?Forcenturieswecouldonlymarv...