Meeting Abstract
Most vertebrates are too heavy to rely on surface tension to traverse the water’s surface. Instead, these animals must use inertial-based mechanisms to produce sufficient hydrodynamic forces to stay afloat. Because these mechanisms are both difficult to employ and size-dependent, few vertebrates are able to perform legged locomotion on the water’s surface. The Indian skipper frog Euphlyctis cyanophlyctis is unique among water surface traversing vertebrates—instead of running, these frogs jump along the water surface. Despite the ubiquity of this species throughout Asia, there have been no quantitative studies on this form of locomotion. To collect the first 3D kinematic data of this water-hopping behavior, we recorded E. cyanophlyctis skittering in a pond on the campus of the National Centre for Biological Sciences in Bangalore, India. We found that the frog readily performs this behavior in the wild, enabling the recording of 109 skittering events over the course of a month. Of these recordings, 60 were deemed suitable for 3D analysis, with the frog traveling through the field of view of multiple spatially-calibrated high-speed cameras. Floating frogs at rest were encouraged to skitter using a hydrodynamic disturbance from below, induced with a telescopic plastic pole. Preliminary analysis of the recordings indicates that these frogs are highly maneuverable while skittering—frogs rarely traveled in a straight line while jumping on water, often turning mid-event towards the pond’s center. Although frogs often jumped in close proximity to one another (sometimes hurdling other frogs), we recorded no frog-on-frog collisions. In this talk, we discuss the techniques involved in 3D field experimentation and highlight the unique locomotor behaviors revealed from the video recordings.
