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Corn snake
A corn snake.
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How do land animals like the corn snake move without legs? Limbless animals tend to be long and slender. One benefit this gives them is the ability to hide in narrow spaces, such as under branches and leaves. To move along flat ground, snakes use a variety of limbless "gaits," similar to a horse's walk, trot and gallop. Researchers at the Georgia Institute of Technology studied the simplest of the snake's gaits: slithering.
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 didn't explain how they can move in areas where there isn't 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)
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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