Snakes have scales on their belly skin which help them move about. On a flat surface, the body weight is continuously redistributed for maximum friction, and the scales provide grip. Researchers at the Georgia Institute of Technology have made detailed studies of the movement of the milk snake. The result, which they call terrestrial lateral undulation, reveals complex motion. On a smooth surface, the snake pushes slightly upward and forward while gripping with its scales. Detailed measurements showed 65 percent of the forward motion comes from contact friction and the other 35 percent from the forward travel while lifting parts of the body just above the surface.
The scales on a snake are arranged like overlapping roof shingles. It was initially thought that the greatest friction would result when pushing backward against the edge of the scales. However, this was not the case. Instead, maximum friction occurs when the scales are pushed sideways. The conclusion is that snakes have the ability to precisely manipulate their belly scales in maneuvering. The scales apparently can be deformed and tilted at will for maximum control of movement.
One promising option for the motion and control of robotics includes scale-like contact surfaces. Continued study of snake mobility will help the design of small crawling robots. Prototypes are called "snake-bots," useful for search and rescue missions. The propulsion of tube-like devices also finds medical application for procedures like colonoscopies.
Berlin, Jeremy. 2010. Slithering Secrets. National Geographic Magazine, March, 217(3):24.
Ehrenberg, Rachel. 2009. Scales provide a smooth slither. Science News 176(1):7.