Meeting Abstract

63-2  Friday, Jan. 5 13:45 – 14:00  Blind sand crabs have visual opsins FAULKES, Z*; SEGURA, S; GARCIA, L; TERRY, J; TERRY, M; The University of Texas Rio Grande Valley; The University of Texas Rio Grande Valley; The University of Texas Rio Grande Valley; The University of Texas Rio Grande Valley; The University of Texas Rio Grande Valley zen.faulkes@utrgv.edu http://doctorzen.net

Sand crabs (Lepidopa benedicti) have a pelagic larval stage with typical compound eyes, but metamorphose into adults with small vestigial eyespots. These adults dig into sand and live under it for the almost all their lives, apparently only emerging into the waters above rarely and by accident. Light penetrates about 6 mm into sand at most, and adults typically bury themselves about 20 mm under sand. When placed in sand so shallow they are unable to cover their eyes, adults showed no preferences for light or dark areas in a tank. Their eyes do not show the typical facets of arthropod compound eyes. Thus, their habitat, behaviour, and morphology is consistent with these animals being blind as adults. But transcriptomes of entire adult sand crab heads contain multiple opsins, including sequences similar short, medium, and long wavelength opsins of other species. We are now using in situ hybridization techniques to determine whether these opsins are expressed in brain tissue and/or the eyes of adult L. benedicti.