One More Way Snakes Can Track Humans Was Just Discovered

A research team in Australia recently debunked a long-standing myth regarding snakes. Contrary to widespread assumptions, snakes are not deaf. Snakes can sense ground vibrations caused by sound waves. This is known as tactile sensing. But, while snakes can feel vibrations, can they hear an airborne sound? This new research proves they can.

The Study’s Parameters

The study included 19 different snakes from seven species. The snakes were placed in a soundproof room. Then, using silence as the control, each snake was exposed to pink noise in three different frequencies: 1–150 hertz (Hz), 150–300 Hz, and 300–450 Hz.

There have been previous studies in which snakes’ movement was restricted by a steel mesh basket when they were exposed to sound. Another study placed electrodes into the brains of anesthetized snakes to measure their cognitive response as sounds were played.

This study, however, mimicked how snakes encounter sound in their natural environment much more closely. The first research investigated how snakes of multiple species would respond to sounds in a space where they could move about freely.

An accelerometer detected whether the sounds produced ground vibrations. Only the lowest frequencies of 1-150 HZ produced such vibrations. The others did not, which is how researchers could conclusively determine that the snakes were responding to airborne sounds and not simply vibrations detected through tactile sensing.

The Study’s Findings

As they were exposed to the sounds, eight different behaviors of the snakes were recorded in the study: body movement, body freezing, head-flicks, tongue-flicks, “periscoping,” head fixation, hissing, and lower jaw drop.

The responses of the different snake species to the sounds varied widely. For example, the woma python (Aspidites ramsayi) moved toward the sound. The snake also displayed a “periscoping” behavior, where the snake raised the front third of its body off the ground to inspect the source of the sound.

But, while the woma python displayed curiosity, others modeled defensive behavior by retreating from the sound. Death adders (Acanthophis), taipans (Oxyuranus), and brown snakes (Pseudonaja) all displayed avoidance behaviors. Interestingly, these three snakes that retreated from the sounds are highly venomous, while the woma python that displayed curiosity and approached the sound source is non-venomous. In their natural habitat, the “retreating” snakes would likely use their hearing to avoid being trampled by large mammals or to escape from their natural predators, such as raptors.

But, whether the snakes displayed curiosity or retreat, the evidence was clear: all of the snakes in the study reacted to airborne sounds.

How Can Snakes Hear Without Ears?

Most mammals, including humans, have an outer ear known as the pinna or auricle. It’s the part of the ear that can be seen and touched.

Snakes obviously do not have outer ears. Snakes do, however, have a single middle ear bone and an inner ear. The inner ear is where sound processing and transmittal take place.

The Australian study reveals that snakes receive, process, and respond to auditory information, not simply tactile sensing of sound vibrations. But, while snakes are certainly not deaf, their hearing is still limited since they lack an outer ear. 

Snakes can only hear frequencies below 600 Hz. A normal human hearing range is 20 to 20,000 Hz. So, while snakes can hear, clearly, they don’t hear as well as we do. Sight and taste (snakes taste the air with their tongues) are the main ways that snakes observe their environment, but we now know that sound plays a role, as well.

Can Snakes Hear Humans?

In a typical conversation, the fundamental frequency of an adult male voice ranges from 80 to 180 Hz. An adult female voice normally ranges from 165 to 255 Hz. In this recent study, the sounds included these frequencies.

The sounds were played at an equal distance from each snake at a level of 85 decibels (dB). A human whisper is about 30 dB. A normal conversation level is around 60 dB. A human shout registers around 80 dB, while a scream can be around 100 dB. 

Long story short, it’s possible that a snake can hear you talk. But a snake can likely hear you shout. And there is conclusive evidence that a snake can certainly hear you scream. 

This will be endlessly interesting for herpetologists, but it may be the stuff of nightmares for ophidiophobians!

The photo featured at the top of this post is © reptiles4all/Shutterstock.com