LESTER, O*; WALKER, JA; Utah State University, Logan; University of Southern Maine, Portland: Does the Action of Multiple Fins Improve Boxfish Turning Performance?

Boxfish have both an exceptional ability to precision maneuver (turn with zero turning radius) and highly derived median and caudal fin anatomy. Throughout sharp turns, the pectoral and median fins continually oscillate, while the caudal fin is held at an acute angle with the body axis. Do the median fin movements and the stereotypical caudal fin position augment turning performance? To explore this question, we investigated how the fins contributed to two measures of swimming maneuverability (minimal turning radius and maximal turning rate) in the boxfish, Ostracion cubicus. Individual fish were treated with some combination of median fin ablation and/or caudal peduncle stiffening. Using a high-speed digital video system, we recorded pre-treatment and post-treatment turning behaviors for each individual. Median fin ablation had no effect on either turning radius or rate. Caudal fin stiffening, either with or without median fin ablation, had no effect on turning radius but decreased turning rate. These results show that the ability to turn sharply in boxfish can be achieved with only the pectoral fins but turning rate can be increased slightly by strong lateral flexion at the caudal peduncle. Funded by ONR N00014-01-1-0506.