Scientist have discovered flying snakes.Flying snake is a misnomer, since, barring a strong updraft, these animals can’t actually gain altitude. Biomechanist Jake Socha of Virginia Tech and his colleagues launched one such species of “flying” snakes, Chrysopelea paradise, from a 15-meter tall tower, then videotaped and analyzed the snakes’ exact body positions throughout their flights.
Four cameras recorded the curious snakes as they glided. This allowed them to create and analyze 3-D reconstructions of the animal’s body positions during flight — work that Socha recently presented at the American Physical Society Division of Fluid Dynamics (DFD) meeting in Long Beach, CA.
The reconstructions were coupled with an analytical model of gliding dynamics and the forces acting on the snakes’ bodies. The analyses revealed that the reptiles, despite traveling up to 24 meters from the launch platform, never achieved an “equilibrium gliding” state — one in which the forces generated by their undulating bodies exactly counteract the force pulling the animals down, causing them to move with constant velocity, at a constant angle from the horizon. Nor did the snakes simply drop to the ground.
Socha explained. “We can now take that information and start making good precise physical and computational models to study the animal’s aerodynamics,” he told The Scientist.
Surprisingly, although the snakes move down toward the ground, the net force on their bodies during the glide is an upward force – at least briefly. That means that if you add up every force acting on the snake, Socha said, you’d be left with a small force pushing the snake skyward.
The snake doesn’t actually start moving up in part because they don’t fly far enough for the net upward force to have an effect, and in part because the upward force disappears quickly, Socha said.
Socha presented his research at the Fluid Dynamics Meeting in Long Beach, Calif., yesterday and today (November 24) published a paper in a special edition of Bioinspiration & Biomimetics. The issue, entitled Bioinspired Flight, includes eight other studies of flying or gliding organisms, including geckoes, seagulls, insects and floating maple seeds, with the aim of improving the design of man-made air vehicles.
There are five recognized species of flying snake, found from western India to the Indonesian archipelago. Knowledge of their behavior in the wild is limited, but they are thought to be highly arboreal, rarely descending from the canopy. The smallest species reach about 2 feet (61 centimeters) in length and the largest grow to 4 feet (1.2 meters).
Their diets are variable depending on their range, but they are known to eat rodents, lizards, frogs, birds, and bats. They are mildly venomous snakes, but their tiny, fixed rear fangs make them harmless to humans.
Scientists don’t know how often or exactly why flying snakes fly, but it’s likely they use their aerobatics to escape predators, to move from tree to tree without having to descend to the forest floor, and possibly even to hunt prey.
One species, the twin-barred tree snake, is thought to be rare in its range, but flying snakes are otherwise quite abundant and have no special conservation status.
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