– Dr Christina Zdenek, Australian Reptile Academy (find her on Instagram @Chris.and.Christina)
There is a long-standing myth that snakes are deaf. Presumably this comes from two places:
- Snakes lack external ear holes, and
- Snakes often stay still as you walk past them.
But neither of these things prove that snakes are deaf. For example, dolphins and moths can hear exceptionally well, yet neither of them have external ears. Regarding point #2, snakes are cowards by default, wanting to escape detection by predators (like humans) whenever possible. This means that they hide most of their lives under cover and try to escape detection via crypsis: staying still to avoid detection. You can walk right past a Death Adder (Acanthophis sp.) without them moving a muscle, which led to their nickname of “deaf adder.” But a lack of reaction still doesn’t mean they’re deaf; maybe the snake is just smart and trying to avoid detection by a massive predator.
With only a trickle of old studies on the topic, and just one species represented under anaesthetic, we decided to put this theory to the test with many free–moving snakes, one at a time. A few of us from The University of Queensland and Australian Reptile Academy partnered with the Creative Industries department at the Queensland University of Technology in Brisbane to conduct 304 experimental snake trials inside a (hot) soundproof room – a room usually occupied by musicians in air conditioning, mind you! We wanted to test:
- Whether free-moving, non-anaesthetised snakes were able to detect airborne sounds (as distinct from groundborne vibrations felt by their belly), and
- How did this change their behaviour?
With zero funding, all volunteer time, and many favours, we managed to pull off the world’s first study about how unrestrained and undrugged snakes respond to airborne sound.
So, what did we find??
Snakes exhibited many different behavioural responses to airborne sounds, and these behaviours generally differed by snake type. For example, Taipans (Oxyuranus sp.) became very defensive to the sound, making hissing noises, fixating their heads toward the sound while moving the rest of their body preparing to strike, and dropping their lower jaw in preparation to strike and/or possibly to show their fangs in intimidation. Death Adders, on the other hand, which are basically vipers morphologically but just not genetically, stayed still most of the time, or if they did move, tended to move away from the sound. This makes sense for an ambush predator that is very vulnerable to being trotted on by large animals moving through the environment.
In contrast, our big nocturnal pythons, Woma Pythons (Aspidites ramsayi), became intrigued by the sound and actually went toward the sound more often than not. They also exhibited an interesting behaviour called periscoping: elevating the first third of their body to get a better sense and viewpoint of what’s going on around them. These top-dog predators don’t have much to fear when they’re that big. No nocturnal aerial predators are large enough to get them.
While we convincingly proved snakes can hear airborne sounds, they cannot hear as well as humans. They likely have a more muffled version of what we can hear, and only up to about 800 Hz in sound frequency – so low frequency sounds. For comparison, a human voice is 250 Hz, and a bird call can be as high as 10,000 Hz. The sound probably also needs to be a little bit louder for them to hear it, kind of like as loud as someone screaming. Indeed, media lines about our paper carried titles like, “Snakes can hear you scream!”
Our work is just the tip of the iceberg though. Really, we still know relatively little about snake hearing. And despite no funding agency wanting to support our work, the public thirst for this knowledge was abundantly clear after its publication. The media coverage of our article reached 779M people globally, including being featured on The Stephen Colbert Show in America – the advertising equivalent of $7.1 million AUD ($4.75 million USD). I think that proves it’s time that funding bodies and governments wake up to the fact that people love learning about snakes, so start funding snake research. Without it, their thirst gets quenched by fear mongering, myths, and misinformation.
This article first appeared in The Buzz! Find out more about The Buzz and how to subscribe.
