7
August 2003
Walking on water: The physics of water strider motion
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For any animal to move forward, it must elicit a reaction from the surface across which it moves. This applies to water as well as solid ground. Water striders — insects that walk on water — were thought to rely on generating ripples for their forward propulsion. The problem was that in theory an infant strider is too small to create waves, but eppur si muove, as someone once said in another context. A team from MIT now shows how water striders of all sizes transfer momentum to water mainly via dipolar vortices shed by their driving legs — they row across the surface using their legs as oars. A specially constructed Robostrider was able to mimic the feat, though less elegantly than the real thing. On the cover, a Gerris remigis water strider attracted to light leaves tracks on water stained with thymol blue.
The hydrodynamics of water strider locomotion
DAVID L. HU, BRIAN CHAN & JOHN W. M. BUSH
Nature 424, 663–666 (2003); doi:10.1038/nature01793
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Animal locomotion: How to walk on water
MICHAEL DICKINSON
How the short legs of juvenile water striders propel the insects across
water has perplexed researchers. It now appears that walking on water
shares features with the locomotion of birds, insects and fish.
Nature 424, 621–622 (2003); doi:10.1038/424621a
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