Meeting Abstract

91.2  Saturday, Jan. 7  Propulsive force calculations of a frog jumping from the water’s surface WILKINSON, Kit C.*; NISHIKAWA, Kiisa C.; UYENO, Theodore A.; LEE, David; Northern Arizona University; Northern Arizona University; Valdosta State University; University of Nevada Las Vegas kcw53@nau.edu

The juvenile North American bullfrog or Lithobates catesbeianus has a remarkable ability to generate enough thrust necessary to jump while floating in water, to distances up to several body lengths. This jump mode is used for aerial prey capture, escape from water-filled depressions, and possibly for aquatic predator avoidance and may contribute to the bullfrog’s success at invading new environments. The adult bullfrog is one of the best terrestrial jumpers in the world, jumping over 180cm in a single jump. However, few studies have attempted to analyze thrust production of jumping from an aquatic medium. Here we compare both terrestrial and aquatic jumping of juvenile bullfrogs. We jumped the frogs off a force plate (ATI, Nano 17) to measure ground-reaction forces to calculate terrestrial thrust. We are currently studying the unique aquatic jump using a custom DPIV (Digital Particle Image Velocimetry) system to analyze the flow generated by the jumping frog. Frogs are tested during aerial prey strike and escape response in an aquarium. The aquarium water is seeded with neutrally buoyant particles, illuminated with a green (532nm) laser light sheet. A high speed camera at 125frames/sec. records the flow of particles during the aquatic jump. The video file is converted to single image files. The images are analyzed with software that tracks the flow of particles. The DPIV system software measures vortex ring velocity and is used to calculate thrust. A comparison of the terrestrial and aquatic thrusts will allow a test of our hypothesis that a correlation exists between the thrusts produced in the two jumping modes.