March 28, 2023

Snakes, after all, hear more than we thought

Because they don’t have external ears, many of us might think that snakes don’t have the ability to hear and can only pick up sounds through the vibrations they make. A team of researchers now says that, after all, these reptiles hear a lot more than we think.

Studying the reactions of 19 captive-bred snakes, of five different sexes, to sounds of various frequencies, researchers from Australia reveal that all the animals reacted to the sounds, although they observed differences in behavior between the different sexes.

Christina Zdenek, from the University of Queensland and lead author of the paper published in the journal PLOS One, says this is the first study of snake hearing in which the animals are not anesthetized and can move at will.

Christina Zdenek with a species snake Pseudonaja textilis.
Photo: Chris Hay

“New research has revealed that [as cobras] they even react to sound waves traveling through the air and, possibly, to human voices,” explains the scientist.

One of the sounds created vibrations in the ground, while the other two simply spread through the air. “This means we were able to test both types of ‘hearing’ – tactile hearing through the snakes’ abdominal scales” and the more familiar hearing through the inner ear.

Christina Zdenek and Chris Hay, co-authors of the paper, prepare the area where they will study the snakes’ reactions to sounds.
Photo: Damian Candusso

Reactions were varied, but only one python of its kind Aspiditesmoved towards the sound, while the snakes of the genus acathophis, oxyuranos is Pseudonaja they tended to move away from the source of the sound, a behavior the researchers suggest indicates the animals found the sound threatening. The specimens of the genus oxyuranos they were the ones that showed the most defensive reactions.

The different reactions can be explained by the ecology of each of the species. Znedek points out that the species python Aspidites is a large, mostly nocturnal snake “with fewer predators than smaller species and probably doesn’t need to be as careful, so they tend to come closer to the sound.”

Scientists believe that snakes can also hear sounds that are naturally produced by humans, such as conversations and screams.

Zdenek recalls that “we know very little” about how snakes live their lives and explore the landscapes they inhabit, “but our study shows that sound may be an important part of their sensory repertoire.”

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