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Snakes, Serpentes, are among the most famous carnivorous reptiles. Surely, their long, limbless bodies with distinct anatomy make you wonder, “how does it function?” Over time, this category of animals has undergone various changes, especially anatomical ones.
Did you know that one of the preconceptions that circulate about snakes is that they are deaf? Perhaps the lack of an ear pavilion has led many to believe that the famous reptile is completely deaf. It is true that snakes have special anatomy, and it is precisely this that leads to these dilemmas. So, do snakes have ears?
Yes and no, says a herpetologist at Rutgers University in New Jersey, USA. Like many reptiles, snakes do not have an outer ear structure. However, snakes have earbones in their heads that they use to hear.
When you think of animals, whether it’s a dog or a rabbit, they hear a noise in a different direction and turn their outer ear to better capture the sound in case it happens again. An inner ear is a part where the essence of hearing takes place.
The ears are usually made of three main parts. The outer ear focuses on the sounds in the eardrum, which separates the outer ear from the middle ear. The middle ear contains three bones that transmit sounds from the eardrum to the inner ear through vibrations. And the inner ear converts these vibrations into nerve impulses that are sent to the brain.
Snakes can hear only a limited frequency range
Snakes have neither a middle ear nor an outer ear, according to a 2012 study published in the Journal of Experimental Biology. Although they have no visible ears, snakes have a middle ear bone that connects the inner ear to the jaw. Research has shown that these square bones actually respond to vibrations in the air, in addition to soil vibrations. The concept behind this is that snakes have spinal nerves that perform vibrations in pores and skin. This is known as somatic hearing. This vibration is transferred through the bones to the inner ear, after which the indicators are sent to the brain and interpreted as sound.
In this way, they are able to determine the location of the prey, for example, by the sound waves produced by its movements. The snake immediately and very precisely perceives the movements around it, and perhaps therefore rare are the situations in which it fails to catch its prey. But snakes are not as good at hearing sounds transmitted through the air.
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Snakes have an inner ear, without the eardrum, directly connected to the jaw bone, the square bone. When the reptile is at rest, this bone rests on the ground and moves slightly in response to the surrounding vibrations. So, snakes can only hear a limited frequency range. Snakes are able to hear low frequencies, but not high frequencies, given that those sounds are transmitted mostly through the air. For example, royal pythons are best at hearing frequencies between 80 and 160 Hz. By comparison, the normal human frequency range is from 20 Hz to 20.000 Hz.
If you were swimming and going underwater and someone standing by the pool would call you, you could hear them. You may not be able to see all the details, but that’s how snakes hear at higher frequencies.
The snake’s auditory system
Now that you know that snakes can hear through the vibrations of sound waves, it’s time to learn something about their hearing system, which I told you above, is completely different from ours. As mentioned earlier, over time, snakes have lost various auditory structures, and currently, in their case, one cannot talk about the external ear or eardrum. However, there is an inner ear and its anatomy consists of:
- Auditory nerve fibers;
- Basilar membrane;
- Conduit/cochlear channel;
- Semicircular canals;
This structure of the inner ear is directly connected to the mandible. It consists of Columella Auris, the square bone, and the supra-temporal bone.
These two structures work together to raise awareness of any movement through sound waves.
Can snakes hear us talking?
Using the above information, we can now see that snakes can simply listen to very low sounds. The sensitivity of a snake’s listening is 200-300 Hz, and the common human voice is about 250 Hz. Therefore, we can see that a snake can actually listen to you speak. This helps us understand what are snake owners talking about when they claim that their pet snakes can understand their names, interpret them, and respond.
Then how do they respond to the sound they hear? A snake can only capture sound waves through the air. It’s because their skull feels vibrations whenever a sound wave hits it. Although, a snake seems to hear the low notes more easily than the high ones. The impulses move directly from the skull to their inner ears, and then the vibrations are sensed by the brain and they respond. They don’t respond like people. Snakes respond to vibrations transmitted directly from the air to the skull instead of responding to sound pressure.
Snakes are the kings of sensory abilities
This limited hearing range is not a problem for snakes, largely because they do not use vocalizations to communicate with each other. The vocalizations they make, such as hissing or growling, are at higher frequencies than they hear and are likely intended for birds and mammals.
The main reason snakes do not need sensitive hearing is that they rely on other senses. Their smell is particularly useful. The snake smells using its forked tongue. Using the tongue, it collects particles from the air and then passes them to the Jacobson organ in the mouth to analyze them. The forking of the tongue has the role of giving the snake a kind of sense of direction depending on the smell. The part of the body on which a snake crawls is very sensitive to vibrations, so it can feel very easily when an animal or human approaches.
In terms of vision, it is most developed in species that live in trees, and less developed in species that nest in the ground. Although the sense of sight is not their strong point, snakes can still detect movement. Some snakes have binocular vision, meaning both eyes are used together. In most species, however, the lens moves back and forth to focus the gaze. Apart from the eyes, some snakes such as vipers, pythons, and boas have infrared receptors positioned in deep grooves between the eyes and the nostrils that allow them to see the radiating heat.
So, while they are unable to hear most of the animals around them, snakes are the kings of sensory abilities.