Kim, H. Y., Amauger, J., Jeong, H. B., Lee, D. G., Yang, E. J., Jablonski, P. G.
Some species of semi-aquatic arthropods including water striders and springtails can jump from the water surface to avoid sudden dangers like predator attacks. It was reported recently that the jump of medium-sized water striders is a result of surface-tension dominated interaction of thin cylindrical legs and water, with the leg movement speed nearly optimized to achieve the maximum take-off velocity. Here we describe the mathematical theories to analyze the exquisite feat of nature by combining the review of existing models for floating and jumping and the introduction of the hitherto neglected capillary forces at the cylinder tips. The theoretically predicted body height versus time is shown to match the results of observing the jumps of the water striders and springtail regardless of the length of locomotory appendages. The theoretical framework can be used to understand the design principle of small jumping animals living on water and to develop biomimetic locomotion technology in semi-aquatic environments.