Meeting Abstract
33.8 Sunday, Jan. 5 09:45 Color vision in a deep sea crustacean, the hyperiid amphipod Paraphronima gracilis BALDWIN FERGUS, JL; Smithsonian National Museum of Natural History baldwin-fergusj@si.edu
The mesopelagic realm, oceanic depths of 200 to 1000 meters, is often described as the twilight zone. Here, the struggle to perceive dim down-welling light and bioluminescent point sources and the need to remain unseen have generated a suite of optical adaptations, including a broad variation in eye design. Hyperiid amphipods are abundant members of the mesopelagic fauna worldwide. These small crustaceans are known for their widely varying and fascinating visual adaptations. The two species of the genus Paraphronima are no exception. In these, the eyes dominate the head and body of these small creatures, taking up about 30% of the body size, and featuring a large clear zone with paired retinas near the ventral surface. To better understand visual function in these little known crustaceans, the spectral sensitivity of Paraphronima gracilis (collected from Monterey Bay Canyon) was examined using microspectrophotometry. The primary visual pigment present in the eye has a λ max of 497 nm (N=118). A short wavelength photopigment with a λmax between 360 and 380 nm was only found in two of the animals sampled (N=15). The results suggest sensitivity to both short and medium wavelength light and imply the possibility of color vision. Results will be discussed in regard to habitat and lifestyle.
