Meeting Abstract
Inking is a dramatic predator defense system that has interesting neuroecological relevance. When ink is used as a predatory defense, it affects predators visually (as a smoke screen) and chemically (as a deterrent), which may be used to disrupt the reception of chemicals or by being aversive to the predators. However, the physiological mechanisms of ink as a deterrent are still poorly understood. The use of ink as a defense is known for a variety of animals such as: sea hares, cephalopods, and even whales. To determine how ink acts as a chemical deterrent, ink from California sea hares (Aplysia californica), common cuttlefish (Sepia officinalis) and pygmy sperm whales (Kogia breviceps) were introduced into the path of free swimming bonnethead sharks (Sphyrna tiburo). Bonnethead sharks are abundant in local waters, are well suited for captivity, and have broad cephalofoils that provide easy access to their olfactory systems. Moreover, the olfactory system of bonnethead sharks is well known, allowing us to further test this sensory system to provide answers regarding the antipredatory function of ink. Sharks were individually placed in a circular mesocosm with a camera mounted overhead. Locomotory kinematic variables (e.g., swimming path, turning radius, angular velocity, etc.) were recorded in response to each of the experimental treatments: the three inks, food odor, food coloring, and sea water. Kinematic variables were used to test the hypothesis that ink negatively impacts swimming behavior. Preliminary data shows sharks change their swimming pattern upon introduction of ink into the water. This reaction confirms that ink negatively impacts shark swimming behavior and supports the hypothesis that ink is used as a deterrent. Future studies will address the ability of ink to deter a predation event and the electrophysiological reaction of shark olfactory systems to ink
