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Desert Diary

Arthropods/Water Strider


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People often indicate their doubts about someone by saying something along the line of, "Boy, to hear people talk, you'd think he walked on water!" This suggests that walking on water is impossible without divine intervention. However, even leaving aside the thought that people in northern climes regularly walk on water during the cold, winter months, some creatures don't find it at all difficult.

Next time you're in a backwater of the Rio Grande, keep your eyes open for water striders. These bugs navigate easily across the surface of the water in search of prey without sinking. How? By utilizing the surface tension of water. Water molecules attract each other through what are called hydrogen bonds. Surface molecules are attracted not only to the water molecules below them, but also are tenuously hitched to those on every side. As a result, light objects can support themselves much as if they were walking on an ultra-thin, weak top surface of a water bed. Remember your mother telling you not to jump on the bed? Goes double, here!

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Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.



Web Resources

Common Water Strider