Here’s how flying snakes stay aloft

The movie Snakes on a Plane had it wrong. That’s not how snakes fly.

Certain species of tree snakes can glide through the air, undulating their bodies as they soar from tree to tree. That wriggling isn’t an attempt to replicate how the reptiles slither across land or swim through water. The contortions are essential for stable gliding, mechanical engineer Isaac Yeaton and colleagues report June 29 in Nature Physics.

“They have evolved this ability to glide, and it’s pretty spectacular,” says Yeaton, of Johns Hopkins University Applied Physics Laboratory in Laurel, Md. Paradise tree snakes (Chrysopelea paradisi) fling themselves from branches, leaping distances of 10 meters or more (SN: 8/7/02). To record the snakes’ twists and turns, Yeaton, then at Virginia Tech in Blacksburg, and colleagues affixed reflective tape on the snakes’ backs and used high-speed cameras to capture the motion.

Physicists had previously discovered that the tree snakes flatten their bodies as they leap, generating lift (SN: 1/29/14). The new experiment reveals that the snakes also exert a complex combination of movements as they soar. Gliding snakes undulate their bodies both side to side and up and down, the researchers found, and move their tails above and below the level of their heads.

Once the researchers had mapped out the snakes’ acrobatics, they created a computer simulation of gliding snakes. In the simulation, snakes that undulated flew similarly to the real-life snakes. But those that didn’t wriggle failed spectacularly, rotating to the side or falling head over tail, rather than maintaining a graceful, stable glide.

If confined to a single plane instead of wriggling in three dimensions, the snakes would tumble. So snakes on a plane won’t fly.