Meeting Abstract

81.6  Sunday, Jan. 6  The Hydrodynamics of Olfaction in the Hammerhead Shark (Sphyrna tudes) RYGG, A.D.*; COX, J.P.L.; ABEL, R.; WEBB, A.G.; SMITH, N.B.; CRAVEN, B.A.; The Pennsylvania State University; University of Bath; Natural History Museum, London; Leiden University Medical Center; Leiden University Medical Center; The Pennsylvania State University adr5023@psu.edu

The hammerhead shark is widely known for its unique head morphology, which is thought to facilitate enhanced olfactory performance. The nasal chambers, located at the distal ends of the cephalofoil, contain numerous lamellae that increase the surface area for olfaction. Functionally, for the hammerhead to detect chemical stimuli, water-borne odors must reach the sensory epithelium that lines these lamellae. Thus, odorant transport from the external aquatic environment to the sensory epithelium is the first critical step in olfaction. Here we investigate the hydrodynamics of olfaction in the hammerhead shark based on an anatomically-accurate, three-dimensional reconstruction of the head and nasal chamber of Sphyrna tudes from high-resolution computed tomographic (CT) and magnetic resonance imaging (MRI) scans of a cadaver specimen. Using this reconstructed model, high-fidelity computational fluid dynamics (CFD) simulations are used to elucidate the external and internal hydrodynamics of olfaction during swimming. Computed external flow patterns reveal the occurrence of flow phenomena that results in high and low pressures at the incurrent and excurrent nostrils, respectively, which induces flow through the nasal chamber. Internal hydrodynamic flow patterns within the nasal chamber are also revealed and the implications regarding olfaction are discussed. Finally, we consider the effect of swimming speed on the hydrodynamics of olfaction, where we show the functional trade-offs of fast- versus slow-speed swimming.