When threatened, the dwarf reed snake can somersault away from danger. The head-over-tail tumble is the first type of active rolling motion documented in any snake or reptile.
Most snakes defend themselves by hissing, striking or slithering away from predators. But dwarf reed snakes (Pseudorabdion longiceps) – native to forests of South-East Asia – take a more creative approach.
“I had observed a dwarf reed snake perform this behaviour once prior to this report but did not have the equipment at the time to record it. It was such a surprising behaviour to watch, and it really stuck with me,” says Evan S. H. Quah at University Malaysia Sabah. “This time, we had our camera gear in hand.”
In August 2019, Quah and his colleagues found an adult dwarf reed snake crossing a road in Kedah, Malaysia. When they approached, the snake began tumbling. First, it contorted into an S-shape, then lifted the front half of its body off the ground. Pushing off from its tail, the snake became entirely airborne. Just when its head looked like it would hit the ground, the snake rapidly tucked under and coiled into a circle. As it made a full rotation, it pushed off the ground again.
The snake travelled around a metre and a half downhill in 5 seconds – far faster than it could have by slithering. While some snakes will let gravity carry them down a slope, called passive rolling, dwarf reed snakes are actively and repeatedly launching their bodies into the air in a move Quah calls a cartwheel. Because this escape method requires a lot of energy, Quah suspects snakes are tumbling away only when very spooked.
“I’ve seen snakes do a lot of weird things… but nothing like this,” says Frank Burbrink at the American Museum of Natural History in New York. “It’s a pretty shocking behaviour that shows us that even in the year 2023, there are so many things left to be discovered with snakes.”
Quah wants to investigate if other snakes can travel this way, too. “There are only anecdotal reports of a few other species from the same family, Calamariinae, that can cartwheel,” says Quah. Now, he just needs to get them on camera.