12.3 Wednesday, Jan. 4 The visual function of the fluorescent lenses of Greeneye fish GAGNON, Yakir*; SPEISER, Daniel; SWEENEY, Alison; Duke Univesity; University of California, Santa Barbara; University of California, Santa Barbara email@example.com
The deep-sea environment is home for a variety of unique and strange animals all adapted to the dim-light environment. Many complex adaptations have developed in response to these unique conditions. Among these are transparency, cryptic coloration, mirrored body, and counter illumination. Counter adaptations for breaking these camouflage strategies include polarization vision, colored ocular filters, and offset visual pigments. The Greeneye deep-sea fish, Chlorophthalmus, is typically found at depths of 50-1000 m. While it is known to have green lenses, the function of these unique lenses is not well understood. To better understand the physiology and visual system of the Greeneye fish, specimens were collected from the Sea of Cortez at depths of 800 m during June 2008. A spectral analysis of the lenses demonstrated strong fluorescence with an excitation peak at 410 nm and emission peaks at 480 and 530 nm. Microspectrophotometry recordings from the retina revealed that the fish’s photoreceptors have a well-correlated maximum absorbance wavelength of about 480 nm. In addition, preliminary results indicate the lens can create an image from photons originating from this fluorescence, blue (410 nm) images are converted by the lens to green (480-530 nm) ones, preserving the spatial information of the images. The spatial integrity of signals at the excitation wavelength (410 nm) is thus preserved and the signal is converted to the maximum absorbance wavelength of the retina (480 nm). We therefore believe that the Greeneye's visual system achieves an exceptionally broad spectral sensitivity (400-500 nm) using only one photoreceptor type, allowing the fish to be visually sensitive to a wide range of differently colored bioluminescent animals as well as the downwelling light.