A study of the surprisingly complex mechanisms behind snakes’ ability to hear has found that despite previous assumptions, many snakes can hear airborne sounds in addition to perceiving ground vibrations.
It is widely accepted that since snakes do not have an external ear, they perceive sound waves only through ground vibrations through their abdominal scales. While that hasn’t changed with the new discovery, new research by a team at the University of Queensland has revealed that some species also respond to sounds traveling through the air.
The team performed 304 experiments on 19 captured Australian snakes, including five genera of snakes (Acanthophis, Aspidites, Hoplocephalus, Oxyuranus and Pseudonaja). Examples included arboreal and terrestrial snakes, as well as heavy-bodied snakes and smaller venomous species.
In a carefully constructed laboratory space that allowed the researchers to stay at a safe distance from the more dangerous snake species, they were able to notice even minor responses to the various Hertz sounds presented.
The team coded nine snake behaviors that could indicate auditory responses by making various sounds from different parts of the experimental enclosure. All of the studied species showed cross-sex-specific responses to airborne sounds.
While all species were observed to move away from the sound, the only species that seemed to move towards the source of the sound were woma pythons (Aspidites).
Lead author of the study, Dr. “Woma pythons are large nocturnal snakes that have fewer predators than smaller species, and they probably don’t need to be that careful, so they tend to get closer to the sound,” Christine Zdenek said in a statement.
These breed-specific behaviors have also been observed in the responses of Taipans (Oxyuranus), which appear to be significantly more cautious and defensive to airborne sounds. Dr. Zdenek says, “taipans may have to worry about predators that are their prey, and they also actively pursue their prey, so their senses seem to be much more sensitive.”
Researchers estimate that breed identity explains more than 88 percent of response behaviors. However, a significant 3.6 percent reacted according to the Hertz frequency of the sound and exhibited different reactive behavior depending on whether the sound was traveling in air or in ground vibrations.
While the exact function of this ability is still unclear, the animals used in the study showed different responses to sounds depending on the species. These different response behaviors suggest that hearing abilities are adapted to suit species-specific needs and behaviors.
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