Meeting Abstract
Bioluminescence is an important mediator of animal interaction in the deep sea. The forms and functions of bioluminescence are diverse, even among groups with shared evolutionary and ecological histories. In one such family of deep-sea shrimps, the Sergestidae (“sergestes” subgroup), light organs known as organs of Pesta have undergone species-specific diversification in morphology. However, the predicted function of these organs in counterillumination (a form of camouflage) has no obvious requirement for this variation, leading to the question: have light organs diversified across “sergestes” to serve as visual signals in conspecific recognition? Here, we examined different aspects of “sergestes” vision to assess their capacity to detect differences in their bioluminescent emissions. Selecting species with distinct organ morphologies (Allosergestes sargassi, Parasergestes armatus, and Deosergestes henseni), we examined eye to body size scaling relationships, as well as eye morphometrics for models of visual ability. Altogether, the conspecific recognition hypothesis was not supported. We found no sexual dimorphism in eye investment, which scales negatively with body growth across all species. Sighting distance models indicated relatively short distances (<1 m) over which these shrimps can detect each other’s general bioluminescence output. After estimating the spatial resolution of “sergestes” vision, images of conspecific appearance rendered using ‘AcuityView’ software suggested the inability of these species to resolve variation in organ morphology. While bioluminescent patterns may not permit species discrimination, it may aid in localizing individuals over short distances; and thus, is capable of serving camouflage and visual signaling in this group, simultaneously.
