'Flying' Snakes Are Actually Legless Gliders

Flying animals are common, but not particularly diverse. Birds, bats, insects and pterosaurs (extinct dinosaur relatives withcomplex wing membranes) are the only four groups of organisms that've ever evolved the ability to fly.

Even so, the sky's not the limit for "flying"snakesin the genusChrysopelea.While these reptiles can't actually fly, they "fall with style" (props to Buzz Lightyear from "Toy Story"), gliding over longhorizontal distances— despite their lack of wings. And, you know,legs.

Life in the Trees

FiveChrysopeleasnakes have been discovered in total. The smallest is the 2-foot (61-centimeter)banded flying snakeand the biggest species, called theornateor "golden" flying snake, can get to be 4 feet (1.6 meters) long. Rounding out this little quintet are theparadise tree snake,Moluccan flying snakeandIndian flying snake.

完美的树上,飞蛇出现在the rainforests ofsouthern and southeastern Asia. Being gliders — and not true flyers —Chrysopeleasnakes don'tproduce thrustwhen they go airborne. That renders them incapable of traveling upwards through the air.

Some of their neighbors have the same problem. Gliders arestunningly commonin Asia's southeastern rainforests. Besides "flying" snakes, these ecosystems include gliding squirrels, gliding frogs and various gliding lizards.

Biologists don't know what makes the trait so widespread here. But that might have something to do with dipterocarp trees. Common in southeastern Asia, these plants can grow 197 feet (60 meters) tall. The lower halves of their trunks are pretty muchbranchless— which is ahugeinconvenience for tree-climbing animals.

Maybe all these unrelated crittersevolvedthe ability to glide as a way of getting from treetop to treetop more easily. It sure beats scampering up and down limbless trunks all day.

The Mechanics of Gliding

Flying snakes have mysterious habits out in the wild. "We actually don't know why they glide — there are no studies that address the topic. (I have been interested for years)," saysherpetologist Jake Sochain an email.

"But anecdotally," he says, "I have seen them use it for escape, from me and other people. And it is also possible and likely that they use it for effective locomotion — to move to another tree or to the ground in a short time, or to avoid slithering over substrates where they could encounter a predator."

A professor at Virginia Tech, Socha has been studying these snakes forover two decades. This past summer, he co-authored a new paper about their aerial antics.

When a flying snake launches itself off of some tree or elevated surface, its ribs splay outwards,flatteningthe animal from the neck to the nether regions. The process helpsChrysopelea蛇产生升力,an upward-acting physical force thatairplanestake advantage of — by making their bodies more aerodynamic.

What this does to their internal organs isanother mystery. At all rates, the methodgets results: Flying snakes have been seen gliding across distances of up to 330 feet (100 meters) horizontally.

Flying Snakes Are Masters of Skillful Slithering

That flying snakes slither while they glide begs an interesting question. Do the reptiles undulate in midair because it helps the gliding process? Or is it just a useless habit, a behavioral relic of some kind or other?

A 2020 study by Sochapublished in the journal Nature Physics— which he co-wrote with engineers Isaac J. Yeaton, Shane D. Ross and Grant A. Baumgardner — tackles this very issue and explores the wayChrysopeleasnakes move through the air.

The researchers observed seven paradise tree snakes gliding in a controlled, indoor setting (specifically, a four-storyblack box theaterat Virginia Tech). Using high-speed cameras and motion-capture tech, they broke down the "flight" choreography. That, in turn, allowed them to build a 3D digital model of the reptiles.

A flying snake will undulate both horizontallyandvertically while it glides. Simulations with the 3D model showed that this complex form of slitheringkeeps the snakes stableduring their airborne treks.

Earlier studies had revealedChrysopelea蛇可以change directionin mid-glide. We've also learned that the creatures will often dangle from a tree limb and twist the fronts of their bodies into a distinct,"J-shaped" loopright before taking off.

Fangs and Food Options

Colubridsare the biggest modern serpent family, with their ranks including familiar favorites likecorn snakes, garter snakes and kingsnakes. Flying snakes belong to this group as well.

You may be wondering if the gliders carry any venom. Indeed they do, butChrysopeleavenom isn't dangerous to humans. (At worst, it might give you a swollen thumb.) Flying snakes are "opisthoglyphous," meaning the fangs that inject their venom are situated near theback of the mouth.

The creatures are diurnal, hunting birds, bats, lizards and frogs in broad daylight. They climb up trees by using their belly scales to grab ahold of bark and other rough surfaces on the trunk. According to Socha'swebsite, none of the five known species are deemed "endangered," though herpetologists have expressed a bit of concern about how the banded flying might be faring these days.