Meeting Abstract

P1-46  Friday, Jan. 4 15:30 – 17:30  Fluid Dynamics of Hammerhead Shark Locomotion HUBER, D.*; CUNNINGHAM, T.; CASARETO, S.; AMPLO, H.; FORD, J.; DECKER, S.; MARA, K.; The University of Tampa; The University of Tampa; The University of Tampa; New Jersey Institute of Technology; University of South Florida; University of South Florida; University of Southern Indiana dhuber@ut.edu

The hammerhead sharks are characterized by an extremely unusual head morphology, the cephalofoil, the function of which has long been debated. While advantages have been identified for sensory systems, the role of this structure in locomotion is poorly understood. Therefore, we sought to quantify the effect of cephalofoil shape on fluid drag. The heads of six hammerhead species of varying cephalofoil morphologies were CT scanned, digitally reconstructed, and 3D printed. Fluid drag was then experimentally measured on each head model while varying angle of attack (i.e., pitch, yaw, roll from 0–35 degrees) in a recirculating flume. Drag coefficient, a measure of the effect of shape on drag, was derived from these measurements. Preliminary results indicate that fluid drag is affected by cephalofoil shape. The largest mean drag coefficient for pitch was associated with the largest, most ancestral cephalofoil of the winghead shark Eusphyrna blochii, whereas the smallest mean drag coefficient for pitch was associated with the smallest, most derived cephalofoil of the bonnethead shark Sphyrna tiburo. Mean drag coefficients were linearly related to cephalofoil width, indicating that drag reduction may be a selective pressure in the reduction of cephalofoil size. All species also demonstrated a reduction in drag force and drag coefficient at positive pitch angles, which supports the observation that sharks maintain positive angles of attack during swimming to generate lift with the ventral body surface.