Fluorescence in an Inclusive Community and Inducible Fluorescence in the Polychaete Species Dodecaceria concharum and Abarenicola pacifica

Abstract

Fluorescence in marine organisms is a common phenomenon, yet the anatomical structures from which it originates and the behavioral function behind it are not well understood. This study had two distinct purposes; to survey fluorescence in a marine fouling community and to describe inducible fluorescence in two Polychaete species. In the first part of the study, organisms were collected, the fluorescence was photographed, the morphological feature(s) that fluoresced was identified and the wavelength was characterized when possible. The functional morphology of the fluorescent structures was then considered to determine if the fluorescence might have a behavioral purpose, although no clear correlations were found. Eight species in four phyla fluoresced in green, orange and red wavelengths. The second part of the study identified the anatomical source of inducible fluorescence and the stimulus which caused its release in two Polychaete worms, Abarenicola pacifica and Dodecaceria concharum. The fluorescence in A. pacifica was found to be mucus secreted from a pore dorsal to the parapodia during dissection and tactile stimulation. In both A. pacifica and D. concharum, the density of the fluorescence coupled with its secretion without puncture of coelomic cavities or blood vessels suggested it was mucus, although due to optical constraints the anatomical origin in D. concharum could not be determined. Chemosensory cues did not induce either species to release fluorescent material, but tactile stimuli did, including human fingers, shells and predators, suggesting a potential defense mechanism.