Although seeing and tasting (the air) are the main ways snakes sense their environment, our study highlights that hearing still plays an important role in snakes’ sensory repertoire.
This makes sense from an evolutionary perspective. Snakes are susceptible to predators including monitor lizards, cats, dogs and other snakes. Hearing is an important sense for both predator avoidance and injury avoidance (such as being stepped on).
For our experiments, we collaborated with the Queensland University of Technology’s School of Creative Practice to outfit a soundproof room and test one snake at a time.
Using silence as our control, we played one of three sounds, each including a range of frequencies: 1-150Hz, 150-300Hz and 300-450Hz. For comparison, the human voice range is about 100-250Hz, and birds chirp at about 8,000Hz.
In one previous studyresearchers hung western diamondback rattlesnakes (A terrible rattlesnake) in a steel mesh basket and observed their restricted behaviors in response to sound frequencies between 200Hz and 400Hz. In another, researchers surgically implanted electrodes into the brains of partially anesthetized snakes, detecting electrical potentials in response to sound up to 600Hz.
But our research is the first to investigate how multiple snake species respond to sounds in a space where they can move freely. We also used an accelerometer to detect whether the sounds produced ground vibrations. In this way we confirmed the snakes were indeed registering airborne sounds, and not just feeling ground vibrations.