Meeting Abstract
Inking is an antipredator defense system which affects predators visually (as a smoke screen) and chemically (as a deterrent). As a chemical deterrent, ink is thought to either disrupt the reception of chemicals or act aversively to a predator’s chemosensory systems. The use of ink as a defense is known for a variety of animals such as sea hares, cephalopods, and even whales. We hypothesized that ink acts as a chemical deterrent, negatively impacting the normal swimming behavior of bonnethead sharks. 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). Sharks (n=7) were individually placed in a circular mesocosm with a GoPro camera mounted overhead. Locomotory kinematic variables (e.g. angular velocity, angle of deviation, seconds to max deviation, distance of max deviation, etc.) were recorded in response to each of the experimental treatments: the three inks, food odor (to test for a positive response), food coloring (to control for color), and sea water (to control for mechanosensory stimulation). Food odor provoked a significantly positive effect while all three inks elicited significant negative responses in at least one of the kinematic variables. These data confirm that ink negatively impacts shark swimming behavior. Future studies will address the ability of ink to deter a predation event, the chemical makeup of the ink, and the electrophysiological reaction of shark olfactory systems to ink.
