SCIENCE LAB SHUTTLE

LATERAL MOVES

Starting to unpeel the skin-deep physics of sidewinder snakes :

When it comes to slithering, most snakes do it the same way : straight ahead. But for snakes that live in deserts, getting around can be a challenge.

''As we know from trying to move on sand in a beach or other places, it can be difficult to move on these materials that yield underneath you as you move forward,'' said Jennifer Rieser, a professor of Physics at Emory University in Atlanta.

That's why sidewinders slither sideways. Although some snakes can move laterally under certain conditions, Dr. Rieser said, sidewinders - the common name for a group of three distantly related vipers found in the deserts of Africa, the Middle East and North America - have raised this unique form of movement to an art.

The sidewinder rattlesnake, for example, can travel at speeds of 18 miles an hour, making it the world's fastest snake.

Now, recently published research by Dr. Rieser and her colleagues may have uncovered their secret : scales packed with tiny pits, instead of the minuscule found on the bottom of other snakes.

The microstructure of snake bellies is important to how they move, Dr. Rieser said, because that's how limbless animals interact with the ground.

To examine the microstructure of sidewinder scales, her team used an atomic force microscope to scan naturally shed snake skins, provided by institutions such as Atlanta Zoo.

They then build mathematical models to test how the structures they saw would perform under different kinds of friction. [Asher Elbein]