Snakes can hear better than we thought

Researchers find that snakes respond to airborne sound and that the reactions depend on the genus.

A woma python in the wild. | Photo Credit: Dr Christina Zdenek, University of Queensland

ONE was always told that snakes’ response to a snake charmer was only visual and not auditory. Researchers at the University of Queensland, Australia, have found that snakes can hear and respond to airborne sound. Christina Zdenek, from the university’s School of Biological Sciences, in collaboration with Damian Candusso, of the Queensland University of Technology, played three different sound frequencies to captive-bred snakes one at a time in a soundproof room and observed their reactions.

“Because snakes don’t have external ears, people typically think they’re deaf and can only feel vibrations through the ground and into their bodies,” Zdenek said. “But our research—the first of its kind using non-anaesthetised, freely moving snakes—found they do react to sound waves travelling through the air, and possibly human voices.”

“We played one sound which produced ground vibrations, while the other two were airborne only,” Zdenek said. “It meant we were able to test both types of ‘hearing’: tactile hearing through the snakes’ belly scales and airborne through their internal ear.”

The study involved 19 snakes, representing five genetic families of reptile. The reactions were found to be strongly dependent on the genus of the snakes. “Only the woma python [Aspidites] tended to move toward the sound, while taipans [Oxyuranus], brown snakes [Pseudonaja], and especially death adders [Acanthophis] were all more likely to move away from it,” Zdenek said. “The types of behavioural reactions also differed, with taipans in particular more likely to exhibit defensive and cautious responses to sound.”

She added that the different reactions were likely because of evolutionary pressures over millions of years, designed to aid survival and reproduction. “For example, woma pythons are large nocturnal snakes with fewer predators than smaller species and probably don’t need to be as cautious, so they tended to approach sound. But taipans may have to worry about raptor predators and they also actively pursue their prey, so their senses seem to be much more sensitive.”

The experiment suggests that snakes can indeed hear sounds in the frequency range and volume of talking or yelling by humans and perhaps also the snake charmer’s flute. “We know very little about how most snake species navigate situations and landscapes around the world,” Zdenek said. “But our study shows that sound may be an important part of their sensory repertoire. Snakes are very vulnerable, timid creatures that hide most of the time, and we still have so much to learn about them.”

The research has been published in PLOS ONE.