File:Gigantometra gigas upward jump in Natural Habitat Pumat National Park Jump 1.webm

English: The clip shows an example of an upward jump by the giant water strider. The movements are slowed down (0.0375 normal speed). The second smaller water strider jumping belongs to the genus Ptilomera. The movie (C0143) was captured in the field at 239.76fps and saved in the standard format of 29.97fps, which was additionally slowed down to 30% of playback speed.

This is a movie that accompanies the manuscript (paper to be submitted) entitled "Allometry of jumping on water: theoretical model and observations of jumps in large water striders" by Woojoo Kim, Juliette Amauger, Jung Moon Ha, Thai Pham Hong, Duc Anh Tran, Jae Hong Lee, Jinseok Park, Sang-im Lee, Piotr G. Jablonski, Ho-Young Kim Abstract

Current theory for surface-tension dominated jumps, created for small and medium size water strider species and used in bio-inspired engineering, predicts that jumping individuals are able to match their downward leg movement speed to their size and morphology such that they maximize the takeoff speed and minimize the latency to takeoff without breaking the surface. Here, we use empirical observations and theoretical hydrodynamic modeling to show that large species do not conform to this theory and switch (“switching” body size range: ~50 to ~80 mg) to using the surface-breaking rather than surface-tension-based jumps in order to achieve jumping performance sufficient for protecting them from attacking underwater predators. This illustrates that natural selection for a performance that minimizes mortality may break the theoretical scaling relationship predicted from a specific biomechanics leading to a switch/shift to a new biomechanical mechanism that results in an outcome favored by natural selection.

Keywords: water strider, surface tension, jumps, antipredatory, water surface, Gerridae, drag, biomechanics, hydrodynamics, allometry