The paradise tree snake (Chrysopelea paradisi)
Snakes wiggle their bodies to propel themselves on land or through water, but why certain flying snake species do so in the air was unclear. Researchers have now found that this undulation helps the snakes stabilise their bodies, enabling them to glide further.
Isaac Yeaton at Virginia Polytechnic Institute and State University and his colleagues studied the movements of Chrysopelea paradisi, the paradise tree snake, a species that launches itself from the tops of trees and can travel up to 100 metres horizontally in a single glide.
These snakes flatten their bodies by splaying their ribs and wiggle from side to side as they glide, travelling at speeds of about 10 metres per second.
The team studied the movement of seven paradise tree snakes using high-speed motion capture, filming them from above as they launched off an 8.3-metre-high platform to an artificial tree on the ground.
Analysing the snakes’ movements, the researchers found that in mid-air the snakes undulate their bodies in both horizontal and vertical waves, and also bend their bodies to angle their heads upwards and downwards.
The researchers then built a digital 3D model to simulate the snakes’ gliding and to look at what effect undulation had on their flight.
Without undulation, the model showed that the snakes would quickly pitch downwards or pitch and roll, becoming unstable while midair. With it, the majority of simulations showed stable glides.
In other environments, snakes and other animals undulate for locomotion. “They’re pushing against their environment on the ground or they’re pushing against water while swimming, says Yeaton. “If you stop undulating in that case, you stop moving.”
Flying snakes use undulation differently, says Yeaton. “They are using it for stability, not for propulsion.”
Journal reference: Nature Physics, DOI: 10.1038/s41567-020-0935-4
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