Rare cartwheeling escape mechanism discovered in dwarf reed snakes

Researchers unravel the secrets of snake defence mechanisms, from playing dead to launching aerial escapes

Dwarf reed snakes in South-East Asia have developed a unique escape mechanism of cartwheeling to evade predators, as documented by researchers. Photo: Evan Quah

Researchers have documented a unique escape behaviour in the dwarf reed snake (Pseudorabdion longiceps) — cartwheeling.

The snake, found across southern Thailand, Peninsular Malaysia, Singapore, Sumatra, Borneo, the Philippines, and adjacent islands, uses this rare escape mechanism to evade predators.

The dwarf reed snake is a small, secretive, nocturnal species, hiding in leaf litter or beneath logs and rocks during the day. It faces many predators, including birds and other snakes such as coral snakes.

While some other snake species rely on hiding or camouflage, the dwarf reed snake has developed an extraordinary method of evading danger.

Researchers documented the behaviour, which they believe evolved from the saltation, or jumping, behaviour of limbless lizards. The team observed an adult snake cartwheeling about 1.5 metres in less than five seconds, using the rolling motion to rapidly cover ground and escape predators.

The cartwheeling behaviour consists of four phases: prelaunch, primary launch, airborne, and secondary launch. The snake coils its body into an S-shape loop, throws itself off the ground, and launches itself into the air.

As the head and anterior portion of the body touched the ground, terminating the end of the airborne phase, the snake immediately coiled its neck and anterior part of the body to spring itself off the ground again, as the remaining airborne sections of the posterior end of the body and tail looped forward over the snake beyond the head.

The secondary launch phase saw the snake throw its body forwards again, pushing sections of its body against the substrate upon contact. The cartwheeling motion was sustained by the snake repeating the recoil-and-roll manoeuvre.

Pseudorabdion longiceps, also known as the dwarf reed snake, employs an extraordinary cartwheeling behaviour to escape predators, according to researchers who observed the snake's movements in South-East Asia. Photo: Evan Quah

This cartwheeling escape behaviour has also been observed in another instance by an observer at Lenggong, Perak state, who recorded it in a video that was uploaded on to YouTube.

The movements of the P longiceps in this observation fit both the “active” and “passive” forms of rolling observed in nature. Rolling, as a form of movement, is rare in nature and appears to be a secondary form of motion in all known organisms that employ it.

In active rolling, the organism expends its own energy to achieve the rolling movement and is capable of exerting control over its rolling, moving in specific directions. In contrast, passive rolling requires external forces, such as wind or gravity, to drive the movement.

Defensive and escape strategies

In addition to active cartwheeling to escape predators, P longiceps and other snakes may employ other defensive strategies. These may include:

Camouflage: Many snakes have evolved colouration and patterning that help them blend into their surroundings, making them less noticeable to predators.

Hissing and puffing: Some snakes will hiss or puff up their bodies to make themselves appear larger and more intimidating when confronted by a potential predator.

Venom: Many snakes possess venom, which they use to subdue prey and deter predators. The venom can cause various symptoms, ranging from mild to severe, and can even be lethal in some cases.

Striking and biting: When threatened, snakes may strike or bite in self-defence. Even non-venomous snakes can deliver a painful bite, which may deter predators.

Tail rattling: Some snakes, like rattlesnakes, have a specialised tail structure that produces a rattling sound when vibrated. This warns potential predators that the snake is dangerous and should be avoided.

Playing dead: Certain snakes, such as the North American hognose snake, will play dead when threatened. They will roll on to their backs, open their mouths, and emit a foul-smelling musk to make themselves appear unappealing to predators.

Mimicry: Some snakes, like the harmless milk snake, have evolved to closely resemble venomous species, such as the coral snake. This mimicry can help deter predators who mistake them for their more dangerous counterparts.

Burrowing and hiding: Snakes may choose to hide in burrows, crevices, or under vegetation to avoid detection by predators. This strategy allows them to stay out of sight and reduce the likelihood of being attacked.

Fast and agile movement: Many snake species have evolved to be fast and agile, allowing them to quickly escape from potential threats. Speed and manoeuvrability can be crucial for survival in the face of predators.

Social behaviour: Some snakes, like the garter snake, may form aggregations or “knots” for warmth and protection. These gatherings can help deter predators, as the mass of snakes may be too overwhelming to attack.

By employing these various strategies, snakes like P longiceps have evolved to survive and avoid predation in their natural environments. These adaptations are essential for their continued existence and success in the animal kingdom.