How "Jesus Lizards" Walk on Water

November 16, 2004

Interpretation of Jesus Christ's reported ability to walk on water is left to biblical scholars. But scientists have figured out how so-called Jesus lizards are able to scurry across the surfaces of ponds and streams.

The findings improve understanding of the physics involved in walking in general and may have practical use in the development of walking robots.

The Jesus lizards, or basilisk lisards, accomplish the seemingly miraculous act of moving on top of water by generating forces with their feet that keep their bodies both above the surface and upright, according to Shi-Tong Tonia Hsieh. Hsieh is a graduate student in the Department of Organismic and Evolutionary Biology at Harvard University in Massachusetts.

Hsieh and her advisor George Lauder detail the process in today's issue of the journal Proceedings of the National Academy of Sciences.

The finding challenges established rules for the mechanics of legged locomotion, which are mostly known from studies of how animals walk across solid surfaces in a laboratory setting, Hsieh said.

"But how do they run across dirt, gravel, or sand? Without knowing much more, we'd think there's some sort of continuum in the strategy animals use to move across surfaces," she said. "We began to wonder about what happens on a squishy surface like water?"

Robert Full, a professor of integrative biology at the University of California, Berkeley, and expert on animal locomotion, said the lack of answers to such questions is holding up the development of new technologies.

"It's one of the major reasons we can't build effective legged robots," he said.

Jesus Lizards

To find answers, Hsieh and Lauder turned to the basilisk lizard (Basiliscus plumifrons), a skittish tree-dwelling species found in Central America. When frightened by a predator's approach the lizard will drop to the water and run across the surface.

Continued on Next Page >>


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