Behavioral responses of bonnethead sharks (Sphyrna tiburo) to controlled olfactory stimulation

Abstract

Swimming behaviors of bonnethead sharks (Sphyrna tiburo) were observed in response to chemical stimulation. Large volume (10 ml) samples were introduced into the path of swimming sharks. In still water, tight turning and circling were observed while samples introduced in the presence of a water current elicited a swimming pattern of connected loops moving downcurrent. A headmount attached to the shark allowed small volume (0.5 ml) samples to be directed into the olfactory capsules. Stimulation in still water produced the turning and circling behaviors as observed for the large volume samples and stimulation in moving waters produced the same connected loops pattern. Other experiments confirmed that the small volume samples quickly dilute below threshold and therefore the behaviors observed in response to the 0.5 ml samples are swimming patterns released by the chemical signal but are presumed to be modulated by factors other than chemical cues. Additionally, it was demonstrated that bonnethead sharks can ...