The spectral characteristics of luminous marine organisms

Abstract

Measurements of the bioluminescent emission spectra of a wide range of marine animals demonstrate considerable differences between taxa in both the position of the peak emission and the half bandwidth. Although most of the measured spectra are unimodal, some species have either two peaks or one main peak with subsidiary shoulders. Such structured emission spectra are present in several systematic groups and in some cases the emission characteristics have been observed to vary with time. The emission maxima of most species fall within the range 450—490 nm, though maxima from 395-545 nm have been recorded. Species found in the pelagic environment are mostly blue-emitting but there is some indication of relative increase in green-emitting species in the benthic environment. Terrestrial organisms are predominantly yellow-green luminescent. The ecological value of the observed spectral differences is discussed. While the characteristics of the emission spectra have considerable adaptive value for certain functions, some minor spectral variations may not be of ecological significance. Selection for increased quantum efficiency of the luminescence may sometimes predominate over spectral considerations.