Meeting Abstract

51.9  Saturday, Jan. 5  Response of Juvenile Scalloped Hammerhead Sharks to Electric Stimuli KAJIURA, Stephen M*; FITZGERALD, Timothy P; Florida Atlantic University; Environmental Defense kajiura@fau.edu

All elasmobranchs possess an electrosensory system that enables them to detect electric fields in their environment. Although their exquisite sensitivity to weak electric fields is legendary, the determination of their sensitivity (ie. voltage gradient detection threshold) is often derived by extrapolating from a mathematical model of the charge distribution for an ideal dipole. This study empirically measured the electric field intensity of a dipole in seawater and confirmed the close correspondence with the model. From this, it is possible to predict how the sharks will respond to dipolar electric fields comprised of differing parameters. We tested these predictions by exposing sharks to different sized dipoles and levels of applied current that simulated the bioelectric fields of their natural prey items. The sharks initiated responses from a significantly greater distance with larger dipole sizes but did not respond from a significantly greater distance with increasing levels of electric current; a result that may be due to the limited range of currents tested. This study is the first to ground-truth a popular model and test predictions about how sharks will respond to a variety of different electric stimuli.