Water-striding insects are able to glide along the surface of water, and make it seem fairly easy. A group of MIT mathematicians worked very diligently to try to understand how they these insects are able to do this. John Bush and David Hu set up small pools of dyed water and used high-speed video cameras to video tape the insects. They observed that they use their center legs to row, although the water high surface tension keeps them from breaking the surface. When they push down on the water, they form a meniscus which is a sort of small valley. Their middle legs press against the back wall of the meniscus , propelling the insect forward. This results in the transfer of momentum to a series of vortices in the water. To prove this theory, Brian Chan built a small robot which used that same technique. It was able to successfully "water-walk". This is an example of discovery based science because the group of mathematicians used their observations to form generalizations. They were trying to understand something they didn't understand, but never set a real hypothesis. The importance of this research is the understanding of one of water many unique properties, surface tension. This experiment explains why some insects are able to stride on the surface of ponds, etc.
By: Stephanie Reynolds
Source:
Fenella Saunders
"How to Walk on Water"
Discover Magazine
November 2003
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