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The Secret of a Snake's Slither (Image 11)


A close view of the scales on a snake

A close view of the scales on a snake.

Have you ever run your hand over a cat's fur? The fur feels smooth in one direction and rough in another. Similarly, the body of a snake is covered with smooth scales that resemble the overlapping shingles on a house. These scales are important for locomotion because they engage with bumps on the ground while the snake is moving. Using simple friction measurements, researchers at the Georgia Institute of Technology found that the arrangement of the scales causes a snake to slide twice as easily when going forward than sideways. This property is called frictional anisotropy. Many everyday items share this property, like wheels, ice skates and cross-country skis. For example, wheels roll easily in a forward direction, but skid in a sideways direction.

Snake locomotion may seem simple compared to walking or galloping, but in reality, it's no easy task to move without legs. Previous research had assumed that snakes move by pushing off of the rocks and debris around them, but that didnt explain how they can move in areas where there isnt anything to push on. Then, a National Science Foundation-supported study (grant PHY 08-48894) by David Hu, a mechanical engineer at Georgia Tech, and his team found that it's all in the snake's design--specifically, their scales.

Overlapping belly scales provide friction with the ground that gives snakes a preferred direction of motion, like the motion of wheels or ice skates. And like wheels and ice skates, sliding forward for snakes takes less work than sliding sideways.

In addition, snakes aren't lying completely flat against the ground as they slither. They redistribute their weight as they move, concentrating it in areas where their bodies can get the most friction with the ground and therefore maximize thrust. In this way, snake slithering is not unlike human walking--we, too, shift our weight from left to right to enable us to move.

To learn more about this research, see the LiveScience article Study shows how snakes slither. (Date of Image: 2009) [Image 11 of 11 related images. Back to Image 1.]

Credit: ©Grace Pryor, Mike Shelley and David Hu, Applied Mathematics Laboratory, New York University, and Department of Mechanical Engineering, Georgia Institute of Technology

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