Making Sense of Shark Senses: Multimodal Integration in Feeding Behavior


Thursday, December 1, 2011
Redfield Auditorium - 12:00 Noon
Ms. Jayne Gardiner
University of South Florida

Our understanding of elasmobranch sensory biology is largely due to studies of individual senses rather than multiple senses working together, leading to important advances in our comprehension of the sensory systems in isolation, but not their complementary and alternating roles in difficult behavioral tasks, such as feeding. .  In this study, three species from different ecological niches were investigated: benthic, suction-feeding nurse sharks hunt nocturnally for fish; ram-biting bonnetheads scoop crustaceans off the bottom of seagrass beds; ram-feeding blacktip sharks rapidly chase down midwater piscivorous prey. We deprived animals of information from the senses (olfaction, vision, mechanoreception, and electroreception), alone and in combination, to elucidate their roles in precisely localizing, striking at, and capturing live prey (capture kinematics). Nurse sharks rely primarily on olfaction for detection. Olfaction in combination with vision, the lateral line, or touch is required for tracking.  Nurse sharks orient to prey using the lateral line, vision, or electroreception, but will not ingest food if olfaction is blocked.  Capture is mediated by the electrosensory system or tactile cues. Bonnetheads normally detect prey using olfaction, rely on olfactory-based tracking until they are close to the prey, then vision to line up a strike, and finally electroreception to time the jaw movements for capture.  They can detect, orient, and strike visually in the absence of olfactory cues. Blacktip sharks also use olfactory olfaction in combination with vision or the lateral line system for tracking.  Long-distance orientation and striking is visually mediated, but detection, short-range orientation and striking can occur visually in the absence of odor cues.  Strike precision relies on lateral line cues and an increase in misses occurs when this system is blocked.  Capture is mediated by electroreception or tactile cues.