Vision in fishes and crustaceans is a fascinating and understudied area. In past decades, there were far more studies on the visual systems of sea-dwelling creatures, but with the push towards applied or translational research, the number of reports in these species have dropped off, much to our detriment as one never knows where the applications of basic research will pay off.
At the same time, the whole study of bioluminescence and vision is an interesting examination of how organisms use bioluminescence for mating, warning or aposematism, crypsis or counter-illumination and predation. It is explicitly a visual phenomenon and as such, has informed a variety of investigations into biomedical, commercial and military applications.
I’ve been going through the literature and found two interesting papers that were published last year in the Journal of Experimental Biology. The first, Light and vision in the deep-sea benthos: I. Bioluminescence at 500-1000m depth in the Bahamian Islands by Sönke Johnsen, Tamara M. Frank, Steven H. D. Haddock, Edith A. Widder and Charles G. Messing and the second, II. Vision in deep-sea crustaceans by Tamara M. Frank, Sönke Johnsen and Thomas W. Cronin. The authors of the first paper investigate the spectral sensitivity and *potential* for color vision in the benthic and benthopelagic species. They collected cnidarians, echinoderms, crustaceans, cephalopods, porifera, and an annelid using the Johnson-Sea-Link submersible, from three sites in the northern Bahamas at 500–1000 m. They also used the Sea-Link to “tap” organisms to stimulate them and elicit bioluminescence.
From their abstract: “Bioluminescent taxa comprised two species of anemone (Actinaria), a new genus and species of flabellate Parazoanthidae (formerly Gerardia sp.) (Zoanthidea), three sea pens (Pennatulacea), three bamboo corals (Alcyonacea), the chrysogorgiid coral Chrysogorgia desbonni (Alcyonacea), the caridean shrimp Parapandalus sp. and Heterocarpus ensifer (Decapoda), two holothuroids (Elasipodida and Aspidochirota) and the ophiuroid Ophiochiton ternispinus (Ophiurida). Except for the ophiuroid and the two shrimp, which emitted blue light (peak wavelengths 470 and 455 nm), all the species produced greener light than that measured in most mesopelagic taxa, with the emissions of the pennatulaceans being strongly shifted towards longer wavelengths. In situ observations suggested that bioluminescence associated with these sites was due primarily to light emitted by bioluminescent planktonic species as they struck filter feeders that extended into the water column”.
The authors of the second paper looked at how crustaceans locate food and determined that they use ultraviolet vision and color discrimination to distinguish the plankton they feed on which bioluminesces in the blue spectrum and the corals that it hunts upon bioluminesce in the blue/green and green spectra. The authors used deep sea submersibles to examine and collect crab species. On collected specimens, they flashed different wavelengths and intensities of light and determined that all deep-sea crab species are sensitive to blue light and two species in particular are sensitive to both blue and ultraviolet light.
Image Credit: A pineapple fish (Cleidopus gloriamaris) that has bioluminescent organs that are packets of symbiotic bacteria (Vibrio fischeri) to generate light. Photographed by Bryan William Jones, Ph.D.