Field-Based Feeding Performance and Kinematics of Bull Sharks, Carcharhinus leucas (Carcharhiniformes: Carcharhinidae)

Abstract

Feeding performance represents a suite of kinematic events and behaviors that achieve the ecologically relevant task of nutrient acquisition. Quantitative accounts of feeding kinematics in large wild sharks are scarce but essential in understanding the ecomorphology of feeding in selachian fishes. This study presents quantitative and qualitative data on bite kinematics and feeding behavior in the Bull Shark, Carcharhinus leucas, using high-speed videography of wild specimens at Cape Eleuthera, The Bahamas. Our results support the hypothesis that bites of carcharhinid sharks, including C. leucas, follow a stereotyped sequence of kinematic events. However, there are interspecific variations in timing and duration of these events. The mean bite duration of 46 recorded bites by Bull Sharks approximately 1.4 m to 1.6 m in total length was 0.29±0.006 s. Bite duration did not vary significantly among the seven study animals, although it was negatively correlated with the angle, or pitch, at which sharks approached food items. The timing of upper jaw protrusion during the bite was correlated with the proximity of conspecifics. We discuss our results in the context of interspecific comparisons of bite performance among macrophagous, ram-feeding elasmobranchs and conclude that body size alone is not sufficient to explain interspecific variations in bite duration. We also discuss the benefits of field-based studies of feeding in sharks as an important complement to more traditional lab-based studies of performance.