A functional analysis of how frogs jump out of water

Euphlyctis cyanophlyctis and E. hexadactylus are two common frog species from south‐east Asia. Both species have the remarkable ability to leap from a floating position out of the water. Rana esculenta is a European species from the same family that barely manages to do so. The species’ morphology, however, looks roughly the same. We studied the unique abilities of the Euphlyctis species by videotaping the three species mentioned above whilst they jumped out of the water. These recordings enabled us to study the hind leg movements and to test several hypotheses. Differences between the species only became apparent when details of the behaviour were analysed. The three species mainly differed in their slip factor at the start of the propulsive phase, resulting in a difference in slip distance. This difference could be traced back to the difference in web shape by means of a physical model. The Euphlyctis species can prevent their feet from slipping because of their rounded and convex webbing, resulting in a larger take‐off velocity and thereby a successful emergence out of the water. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 413–420.