UV Photosensitivity in a Deep-sea Benthic Crab
2006 Ocean Sciences Meeting, Honolulu, Hawaii, February 20-24, 2006
During an Ocean Exploration funded research cruise in the Gulf of Mexico (Operation Deep-Scope 2005), new techniques were used which proved to be very successful at collecting deep-sea benthic crustaceans with intact photoreceptors. Collections were made from Harbor Branch Oceanographic Institution`s Johnson-Sea-Link (JSL) submersible under red and orange illumination, so that collections could be made without blinding the animals. Two collection techniques were used. Baited traps were deployed, together with a decoy bait bag placed some distance away. The decoy was needed to lure away the larger crabs, which would otherwise guard the traps and prevent the smaller crabs from entering them. The traps were recovered on a subsequent dive and deposited into specially constructed black BioBoxes, which are thermally insulating and light tight when closed at depth. In addition, the suction sampler on the arm of the JSL was modified so that crabs could be picked up and deposited directly into a BioBox, which was then sealed for the trip back to the surface. Even though over half the cruise was lost due to Hurricane Katrina, 7 species of crustaceans were collected from bottom depths of 525 to 550 m. These included anomuran crabs Gastroptychus sp., Eumunida picta, Munidopsis tridentata and two unidentified genera, the brachyuran crab Bathynectes longispina, and 1 unidentified caridean shrimp. A surprising discovery, revealed by electrophysiological recordings, was that Gastroptychus has an ultraviolet photoreceptor, in addition to the usual blue receptor. The role of ultraviolet photoreception in such a deep-living crab remains a mystery, but preliminary data from the caridean shrimp suggest that it too possesses UV sensitivity, while E. picta, M. tridentata and B. longispina do not.
Frank, Tamara M., "UV Photosensitivity in a Deep-sea Benthic Crab" (2006). Oceanography Faculty Proceedings, Presentations, Speeches, Lectures. 401.