Meeting Abstract

P2.19  Wednesday, Jan. 5  Orientation of hatchling sea turtles to ocean waves: a virtual reality approach ENDRES, C S*; BUTLER, R; STAPPUT, K; LOHMANN, K J; University of North Carolina, Chapel Hill endres@email.unc.edu

Hatchling loggerhead sea turtles (Caretta caretta) emerge from underground nests on oceanic beaches, scramble to the sea, and migrate offshore by swimming into ocean waves. Because waves entering shallow, coastal areas are refracted until they approach the beach directly, swimming into waves reliably guides turtles away from land and toward the open ocean. Previous experiments demonstrated that turtles perceive wave direction by monitoring the orbital movements that occur under water as waves propagate through the sea. To investigate further how turtles respond to wave movements, a wave motion simulator was constructed to reproduce in air the orbital movements that accompany waves. In addition, a robotic device was produced which monitored the rear flipper movements that occur when turtles try to change course. As a turtle attempted to turn, the device slowly rotated the turtle in response. The device was mounted on the wave simulator, so that the turning behavior of turtles in the presence of orbital movements could be assessed. The results demonstrated that, regardless of the initial alignment of the turtle with respect to the simulated waves, hatchlings turned until they faced into the direction of simulated wave approach. Thus, hatchling sea turtles can determine the propagation direction of ocean waves by monitoring the circular movements that occur as waves pass through the ocean. Although sea turtles are the only animals presently known to perceive wave direction in this way, a similar mechanism may exist in diverse marine animals ranging from invertebrate larvae to fish and marine mammals.