Animals haven’t had direct communication in their lives. Therefore they use a natural Sonar system called “Echolocation”. It means a physical process for locating distant or invisible objects by sound waves reflected by objects to the emitter from the object. Uses of echolocation are orientation, barrier avoidance, food planning, and social interactions. Bats, whales, dolphins, a few birds like the nocturnal Oilbird and some swiftlets, some shrews, and the similar tenrec from Madagascar are echolocating for their needs.
How do bats use echolocation?
Bats make sounds for echolocation in their larynxes and emit them from their mouths. Most bats can be too high-pitched for humans to hear. Some bats scream at up to 140 decibels, as loud as a jet engine 30m away. Bats can recognize an insect up to 5m away, work out its size and hardness, and can avoid wires as fine as human hairs. As a bat closes in for the kill, it cranks up its calls to pinpoint the prey. To avoid being deprived of hearing by its calls, a bat turns off its middle ear just before calling and re-establishes its hearing a split second later to listen for echoes.
How do dolphins use echolocation?
Dolphins are using echolocation by bouncing high-pitched clicking sounds off underwater objects, similar to shouting and listening for echoes. The sounds are made by compressing air through nasal passages near the blowhole. These soundwaves then pass into the forehead, where a big ball of fat called the melon focuses them into a beam. If the echolocating sound hits something or a fish, the reflected sound is picked up through the dolphin’s lower jaw and passed to its ears. Echolocating sounds are so loud that the ears of dolphins are covered to protect them. Dolphins use this method to identify an object’s distance, direction, speed, density and size. Dolphins can detect an object like a golf ball, about the length of a football pitch away – much further than they can see by using echolocation. By moving its head to aim the sound ray at different parts of a fish, a dolphin can differentiate between species. This process is the same as for the whales described below.
How do whales use echolocation?
Echolocation is also important for whales – to navigate, find food, and communicate. The pressure at a depth of 100 meters in the ocean compresses the air. It receives a smaller volume of air than surface air. Using a large volume of air for echolocating consumes a lot of energy to move the sound back and forth. But the volume of air per click means that a whale costs about 40 Joules for a valuable dive click. It is an energy unit. To put that number in perspective, a whale would need about 37,000 Joules to sink its buoyant body to a depth of 600m.
How do other animals use echolocation?
The Oilbird is insect-eating and active at night, swiftlets roost in dark caves, therefore it makes sense for them to have evolved to echolocate. They use sharp, audible clicks to navigate through the darkness.
Hedgehogs use ultrasonic waves. They have got a great hearing, but we have yet been unable to confirm that they echolocate for certain.
Visual and auditory are related because they can process reflected energy waves. Vision is activated when light waves travel through their source, leaping from the surface of the environment and entering the eye. Then the auditory system, as sound waves travel through their source, bounces off the surface and into the ears. Both systems can obtain large amounts of information about the environment by interpreting complex patterns of reflection energy. In terms of sound, the waves of this reflective energy are called “echoes”.
Written By Sasanika Ruwanthi Jayarathna
- Discovery of Sound in the Sea. 2022. How do marine animals use sound?. [online] Available at: https://dosits.org/animals/use-of-sound/how-do-marine-animals-use-sound [Accessed 7 May 2022].
- Encyclopedia Britannica. 2022. echolocation. [online] Available at: https://www.britannica.com/science/echolocation [Accessed 7 May 2022].
- Facts, A., 2022. What is echolocation and which animals use it?. [online] Discover Wildlife. Available at: https://www.discoverwildlife.com/animal-facts/what-is-echolocation [Accessed 7 May 2022].
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