Vision and Bioluminescence in the Deep-sea Benthos

During a NOAA-OER funded research cruise, novel collecting techniques were used to collect live, deep-sea benthic animals for studies of bioluminescence and vision. True color images and emission spectra of bioluminescence were obtained from a number of species, including the spiral octocoral Iridogorgia  sp., the sea fan Chrysogorgia sp., the sea pen Umbellula sp., and the caridean shrimp Heterocarpus oryx. Electrophysiological studies were conducted on 3 species of decapod crustaceans collected with methods that limited light damage to their photoreceptors. The caridean shrimp, Bathypalaemonella, collected from 1920 m, was always found in association with the bioluminescent spiral octocoral Iridogorgia. While moribund at the surface, enough data were obtained from one specimen to show different waveforms in response to short and long wavelength light, indicative of two different classes of photoreceptor cells. The chirostylid crab, Uroptychus nitidus, found in association with the bioluminescent sea fan, Chrysogorgia sp., also appears to possess two visual pigments, and if further analysis of data supports this preliminary observation, will be the 4th species of deep-sea, non-bioluminescent crustaceans possessing two visual pigments found in association with bioluminescent cnidarians. These four species also share another characteristic – the presence of one or two very long claws, which the crab species are known to use to pick items (possibly plankton stuck in the mucus) off their cnidarian hosts. These data support the previously presented hypothesis (Frank et al. 2012), that these crustaceans may be utilizing their dual visual pigment systems to distinguish between prey and host, based on spectral differences between pelagic and benthic bioluminescence.