Tuesday, March 18, 2008
When a Sticky Gecko Starts to Slip...
...Its Tail Comes to the Rescue
By HENRY FOUNTAIN
Published: March 18, 2008
Apart from its ability to hawk car insurance, the gecko has gained renown for its skills as a climber. It can ascend vertical walls and even walk across ceilings, courtesy of its sticky feet.
But the gecko is far from a perfect climber; it can slip at times. And when it does, researchers at the University of California, Berkeley, report in The Proceedings of the National Academy of Sciences, it uses its tail to help recover.
Using slow-motion video (some can be seen at nytimes.com/science), Ardian Jusufi, Robert J. Full and colleagues discovered that the gecko’s tail is a very active appendage, springing into action when things go wrong. When the gecko is climbing vertically and starts to slip, the tail arches and the tip pushes against the surface, which usually prevents the head and upper body from pitching back, away from the wall. If it doesn’t, then most of the tail flattens against the wall. These movements, the researchers showed, stopped the gecko from slipping within a quarter of a second.
When all else failed and geckos fell, the researchers noticed that they always landed right-side up. Cats and other mammals that can right themselves generally do so by twisting their spines. But the researchers’ videos showed that the gecko used its tail, swinging it around while upside down to produce a counter-rotation of the body in about a 10th of a second.
The researchers say the concept of such an active tail has already been incorporated in a four-legged climbing robot, called RiSE, and could inspire future designs of gliding aircraft and spacecraft.
NYT
http://www.nytimes.com/2008/03/18/science/18obgeck.html?ref=science
