A "flying snake" undulating through the air.

The ability to glide has evolved separately in a surprising diversity of animals that stretches from reptiles, mammals, frogs, ants, and fish to even some species of squid. One of the more interesting gliders, however, must be the Chrysopelea, often called the “flying snake”.

Along the west coast of India and in parts of Southeast Asia and Sri Lanka, some snakes can actually glide from tree to tree with such art and grace that it is almost unrealistic when brought up without any factual videos provided. Most would claim that, because snakes are simply long tubes with no arms or legs, they are not capable of gliding through the air without toppling over.

Jake Socha, a biologist at Virginia Tech, reporting his preliminary findings in the August 8 issue of Nature, showed that the snakes flatten and undulate their bodies to glide through the air.

“The undulation is not akin to a flapping wing,” Socha explained. “It’s more like putting a whip on a large table and then moving the whip from side to side, with waves moving down the whip.”

The snakes undulate from side to side, in an almost air-slithering motion, to create an aerodynamic system. This lets them travel from the top of the highest trees (about 200 feet high) to a spot around 780 feet away from the tree’s trunk.

Chrysopelea Ornata

The snake glides by making a J-shape bend and leaning forward to select the level of inclination it desires to move to control its flight path, as well as selecting a desired landing spot. Once it decides on a destination, it propels itself by thrusting its body up and away from the tree, sucking in its stomach, flaring out its ribs to turn its body in a “pseudo concave wing”. During this process, the snake also makes a continual serpentine motion to stabilise its direction in midair in order to land safely.

Flying snakes are able to glide better than many other gliding animals, despite having no arms, legs, wings, or any other wing-like appendages, gliding through the forest and jungle it inhabits with the distance as far as 100 meters.

There are five recognized species of flying snake, found from western India to the Indonesian archipelago. Information about their behavior in the wild is limited, but it is thought that they rarely descend from the canopy. The smallest species reaches about 2 feet in length and the largest grow to about 4 feet.

Sources:

1. New Snake Footage Uncoils Mystery of Flying Serpents, National Geographic News, October 2010.
2. DOD tries to uncover secret of flying snakes, The Washington Post, November 2010.
3. Gliding and the Functional Origins of Flight (PDF), Robert Dudley et al., Annu. Rev. Ecol. Evol. Syst. (2007)
4. Ecological Morphology of Locomotor Performance in Squamate Reptiles (PDF), Theodore Garland Jr. and Jonathan B. Losos, 1994