Snakes are unique animals with their limbless bodies, shaking tongues and the ability to swallow prey whole. They mostly rely on their sense of smell to catch prey, although they also use sight and sound. But do snakes have ears?
Yes and no, said Sarah Rouen, a herpetologist at Rutgers University in New Jersey, to Live Science. Like many reptiles, snakes do not have an external ear structure. However, they have ear bones in their heads that they use to hear.
“When you think of animals, whether it’s a dog or not jack rabbit, they hear noise in different directions and shift their outer ear to better pick up that sound in case it happens again, “Rouen said.”
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The ears usually consist of three main parts. The outer ear focuses the sound on the eardrum, which separates the outer ear from the middle ear. The middle ear contains three bones that transmit sound from the eardrum to the inner ear through vibrations. The inner ear converts these vibrations into nerve impulses that travel to the brain.
Snakes do not have an outer ear and a middle ear, according to a 2012 study Journal of Experimental Biology. However, they have a bone in the middle ear that connects the inner ear to the jaw. This allows snakes to hear vibrations, like a predator crawling closer to the forest floor. However, they are not so good at hearing sounds transmitted through the air.
Due to this tuning of the ears, snakes hear only a narrow range of frequencies. They can hear low frequencies, but not high ones, as these sounds are transmitted mainly through the air. For example, royal pythons are best at hearing frequencies between 80 and 160 Hz, according to a 2012 study. By comparison, the normal human frequency range is 20 Hz to 20,000 Hz, according to “Neurology“(Sinauer Associates, Inc. 2001).
“If you swim and go underwater and someone standing by the pool yells at you, you’ll hear them,” Rouen said. “You may not be able to understand the details … This is something that snakes hear at higher frequencies.”
This narrow range of hearing is not a problem for snakes, in part because they do not use vocalizations to communicate with each other. The vocalizations they make, such as hissing or growling, are higher in frequency than they hear and are likely intended for birds of prey and mammals, according to the study.
The bigger reason snakes don’t need sensitive hearing is that they rely on other senses. Their sense of smell is especially useful. “Snakes bite their tongues, capturing all the odor molecules that are in the air nearby, returning them to a specialized organ they have to process and to their brains,” Rouen said. So, although they don’t have a chance to hear most other animals, “snakes are chemosensory kings.”
Originally published in Live Science.