Dwarf reedsnakes roll at up to 3.69 m/s while keeping their heads steady

Dwarf reedsnakes, small burrowing snakes from Southeast Asia, can roll along the ground at peak speeds of 1.72 to 3.69 metres per second while keeping their heads almost level, according to a study published October 19 in Current Biology by a team led from Toho University in Japan.

That is about four times the peak speed the same snakes reach with lateral undulation, the side-to-side slither most snakes use, the university said.

From curiosity to measurement

Rolling in these snakes, from the genus Pseudorabdion, was already known. A 2023 report described them flinging their bodies into cartwheels to get away from danger, and that work drew wide attention for simply showing the behaviour exists.

The new paper, "Locomotor kinematics and head stabilization in rolling snakes," does something different: it measures how the movement works. The researchers filmed the snakes from several angles as they moved down a narrow track only 20 cm wide, then broke each roll into repeating cycles.

The authors listed on the paper are Yosuke Kojima, Ibuki Fukuyama, Mohamad Yazid Hossman, Clement Het Kaliang and Kanto Nishikawa.

How one roll works

In each cycle, one side of the snake's body rests on the ground while the animal turns over. An arched section of the body then swings down past the side of the head toward the ground, a movement the team calls a "stroke."

Which flank touches down, and which way the stroke swings, alternates from left to right with every cycle, so the snake does not keep turning the same way.

A steady head on a spinning body

The more surprising result concerns the head. While the back part of the body rotates quickly, the head stays pointed in the direction of travel and holds a fairly constant height, especially at higher speeds, according to the release.

A stable head matters for any fast-moving animal, since it keeps the eyes and balance organs from being thrown around. The study suggests the snakes manage this even while most of the body is tumbling.

The release describes the rolling as a way to escape predators but does not say how long the snakes can keep it up, how many animals were filmed, or exactly how the head is held still. Those details may be in the full paper, which was not available to read.