September 29, 2005
For these bugs, walking on water is easy
A "meniscus"--the crescent-shaped and barely visible slope literally at water's edge--can mean life or death to an insect the size of a speck of dust. Water bugs that tiny must summon the energy to "surf" themselves up the problematic interface between liquid and solid in ponds and other wet places to escape predators or reproduce.
Menisci are all around us, "but we don't notice them because they're so small, only a few millimeters in height," said mathematician David Hu of the Massachusetts Institute of Technology. "But if you're a creature that's much smaller than that, those slopes "are like frictionless mountains," said Hu. "Plus, it's slippery."Now, Hu and coworker John Bush have done the math to explain how nearly weightless water walkers find the traction to ascend a wall of water several times their height. Such obstacles, which are almost invisible to humans, may surround a leaf floating in a stream or a stone on the riverbank.
An article on the work appears in the Sept. 29 issue of the journal Nature.
According to Bush, the study, which was funded by the National Science Foundation, may be "of interest to people working in nanotechnology,
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