Different animals use echolocation for different reasons:
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Bats are nocturnal, so are normally hunting when there is little or no light to see by. Similarly, whales spend a lot of their time swimming deep in the ocean where only a small amount of light can reach.
By using echolocation, bats and whales are able to navigate through their environments and can detect objects as thin as a human hair, even in complete darkness.
As they send out soundwaves and listen for the returning echoes, they can begin to ‘see’ the world around them. This allows bats to avoid obstacles like trees and buildings, and lets whales stay aware of objects and other animals nearby. Bats have evolved very sensitive (and sometimes very large) ears, which help them echolocate objects and prey with greater precision.
Some humans have even learned to use a simple form of echolocation. By making clicking sounds with their tongue, some partially sighted or blind people have been able to ‘see’ objects nearby and avoid obstacles in the same way that animals like bats do.
Hunting
Some animals have such effective echolocation abilities that they are able to locate prey in the air around them, swimming by and even buried under the sea floor!
Bats are famous for the nocturnal hunting. Research has found that some species of bat are able to tell different insects apart from each other, avoiding smaller prey in favour of larger meals.
This has led to several species of moth developing defence mechanisms to avoid being eaten.
Some moths have evolved long tail-like wing tips which flick back and forth during flight and make it hard for the bat to tell exactly where they are. Other moths have even developed the ability to make their own ‘echolocation clicks’, which interfere with the bat vocalisations and make them much harder to find in the dark.
Dolphins are another predator renowned for their marine hunting abilities. One species that had refined this skill was the Yangtze River dolphin. Over generations of living in a heavily polluted river with almost no visibility, this animal was able to hunt just as effectively as dolphins in other parts of the world where the water is much clearer. Unfortunately, this species is now thought extinct as of 2002 and scientists believe it is the first species of dolphin ever driven to extinction by human activity.
Along coastlines and shallower waters, some dolphins are able to tell where prey are hiding under the sand and sea floor! The echolocation they produce can penetrate the top layer of sand just enough to know if there’s something tasty trying to stay hidden.