Have you ever wondered how animals who live in darkness are able to detect their surroundings? We know that for something to be seen, there must be the presence of light - whether it is the Sun or a light bulb - that gets reflected from the object into our eyes. However, in the absence of light (or with very little of it), how do these creatures see clearly? In this article, we will learn about the process known as echolocation.
What is echolocation?
According to Britannica (2024), echolocation is a physiological process for locating distant or invisible objects by means of sound waves reflected back to the emitter by the objects. Here is an image that illustrates how echolocation works:
Image of the process of echolocation (Jones, 2016)
Here’s a simple breakdown of the steps:
A sender emits a high pitch sound in the form of sound waves.
A high pitch sound is used as such higher frequencies of sound allows objects to be more clearly ‘seen’. According to Laura Kloepper (cited in Guarino, 2023), the higher the frequency, the smaller the detail captured by the vibration of energy in the air. This allows the receiver to pick up more details about the surroundings.
These sound waves will travel through the surroundings and reach an object.
As the sound waves cannot go through the object, they will get reflected back towards the sender, which is what we call an echo.
When the reflected wave reaches the sender, the distance sensor will analyse the reflected wave and be able to locate the object based on the reflected wave.
Some of its uses include orientation, avoiding obstacles, gathering food and social interactions (Britannica, 2024).
Applications of echolocation
Now, let us take a look at how some animals use echolocation to see.
Using echolocation in the ocean
Some animals who echolocate in the ocean include dolphins and whales. The bottom of the ocean has little to no light, which causes the need to echolocate so that they can navigate their surroundings and find prey more easily. The sound is made by squeezing air through nasal passages near the blowhole, which then pass into the forehead, where a big blob of fat called the melon focuses them into a beam, producing high-pitched clicking sounds (Price, 2022). This is represented by the red arrows in the following image:
Cross-section image of whale using echolocation to find its prey (Gorter, n.d.)
When the sounds hit another object such as a fish, the sound gets reflected, as represented by the blue lines. The reflected sound (in the form of vibrations in the sea) gets transmitted through their lower jaw and received by fat-filled cavities near the inner ears of the animal, which allows the echoing clicks to be sensed (Guarino, 2023). This allows it to determine where the fish is and even how fast it is going.
In addition, echolocating sounds are so loud that the ears of dolphins and whales are shielded to protect them (Price, 2022).
Using echolocation in the air
A famous example of an animal who uses echolocation is a bat. Bats live in dark caves where there is also very little light, making seeing with their eyes very difficult. Other animals who use echolocation include nocturnal oilbirds and swiftlets.
According to Kate Allen (cited in Langley, 2021), for most bats to emit a sound to echolocate, they contract their larynx muscles to make sounds above the range of human hearing. They emit sounds in the form of clicks in order to ‘see’. When they echolocate their prey, they will have to click continuously - sometimes making 190 calls a second - because the latter tend to move very quickly (Langley, 2021). However, similar to the animals underwater, the sounds that bats emit are extremely loud. To avoid being deafened by its own calls, a bat turns off its middle ear just before calling, restoring its hearing a split second later to listen for echoes (Price, 2022).
To see an animation of how bats echolocate, watch this video (SciToons, 2016) to find out more!
Works Cited
Britannica, The Editors of Encyclopaedia Britannica (2024). Echolocation. In: Encyclopedia Britannica. [online] Available at: https://www.britannica.com/science/echolocation. [Accessed on 2 Sept. 2024]
Gorter, U. (n.d.). Echolocation | Smithsonian Ocean. [online] ocean.si.edu. Available at: https://ocean.si.edu/ocean-life/marine-mammals/echolocation. [Accessed on 3 Sept. 2024]
Guarino, B. (2023). How echolocation lets bats, dolphins, and even people navigate by sound. [online] Popular Science. Available at: https://www.popsci.com/science/what-is-echolocation/. [Accessed on 3 Sept. 2024]
Jones, R. (2016). What is Bat Echolocation? - Learn About Nature. [online] Available at: https://www.learnaboutnature.com/mammals/bats/bat-ecolocation/. [Accessed on 3 Sept. 2024]
Langley, L. (2021). Echolocation Is Nature’s built-in sonar. Here’s How It works. [online] National Geographic. Available at: https://www.nationalgeographic.com/animals/article/echolocation-is-nature-built-in-sonar-here-is-how-it-works. [Accessed on 3 Sept. 2024]
Price, J. (2022). What is echolocation and which animals use it? [online] www.discoverwildlife.com. Available at: https://www.discoverwildlife.com/animal-facts/what-is-echolocation. [Accessed on 3 Sept. 2024]
SciToons (2016). Echolocation. [online] www.youtube.com. Available at: https://www.youtube.com/watch?app=desktop&v=laeE4icRYp4 [Accessed on 3 Sept. 2024]
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