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What is echolocation? -

Echolocation is nature's built-in biological sonar. It's a unique auditory tool that some animals use to navigate, hunt, identify other species, and avoid obstacles.

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How does echolocation work? -

These animals emit a high-frequency pulse of sound that bounces off an object, returning an echo that provides information about the object's distance and size. The sound waves also help them navigate even while not being able to see. 

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Bats -

Over 90% of bat species are thought to use echolocation. They use their built-in sonar to pursue fast-flying prey at night. Pictured is a greater horseshoe bat hunting.

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Echolocating -

Bats echolocate to navigate through their habitats, especially noisy environments such as a forest resounding with other animal calls. Pictured is a cloud of fruit bats swarming over Komodo National Park in Indonesia.

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Sound waves -

Most bats produce sound waves in the form of chirps and calls. They do this by contracting their larynx muscles to make sounds above the range of human hearing. Pictured is a Daubenton's bat striking down an insect over water.

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Picking up signals -

A bat's ears are especially designed to recognize their own calls as they echo back. Some species can even rapidly change their ear shape to accurately pick up incoming signals. The brown long-eared bat (pictured) can in fact hunt their prey by hearing alone.

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The bounce back -

Leaf-nosed bats differ in that they emit echolocation calls through their large, intricately folded noses, which helps focus sounds that bounce back.

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Frequency range -

Most bat echolocation occurs beyond the range of human hearing. Humans can hear from 20 Hz to 15-20 kHz depending on age. Frequency is measured in the unit hertz (Hz), referring to a number of cycles per second. One thousand hertz is referred to as a kilohertz (kHz). Bat calls can range from 9 kHz to to 200 kHz, which gives species like the big brown bat (pictured) a distinct edge on the wing.

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Whales -

Nowhere is echolocation used more logically as a strategy than in the ocean, where sound travels nearly five times faster than in air.

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Echolocating under water -

Toothed whales echolocate via a specialized organ called the dorsal bursae, which sits at the top of their head, close to the blowhole. Sperm whales produce clicks within the 10 kHz to 30 kHz frequency range at quick intervals between 0.5 to 2.0 seconds during their deep dives.

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Vocalizations -

Beluga whales are extremely vocal. The frequency and large repertoire of their vocalizations have earned them the nickname "sea canaries." Belugas will change the frequency of their echolocation signals depending on the amount of ambient noise in the area they are swimming in.

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Whistles, clicks, and calls -

Orcas, or killer whales, produce a cacophony of sound—whistles, clicks, pulsed calls, low-frequency pops, and jaw claps. Many of these calls function in group recognition and coordination of behavior, especially when hunting. Their echolocation clicks at low frequency peak between 20 kHz to 30 kHz. High frequency peaks between 40 kHz to 60 kHz.

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Directional sonar -

Known as the "unicorn of the sea," the narwhal possesses the most powerful directional sonar of any animal on Earth. Narwhals live year round in Arctic waters, an environment that is often dark and frozen. Surfacing frequently for air, the whale has to precisely pinpoint small holes and cracks in the ice through which to grab quick gulps of air.

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Dolphins -

Dolphins propel ultrasound into fatty structures at the front of their heads, called melons. These, in turn, efficiently transmit vibrations in water that bounce off prey and other objects. This way the mammal can select a specific target and track it over varying distances.

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Using ultrasound -

Most dolphins, the Atlantic spotted dolphin included, start with a low frequency ranging between 40 and 50 kHz to communicate, but emit a much higher frequency signal—between 100 and 130 kHz—while echolocating.

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Loud and louder -

Incredibly, echolocating sounds are so loud that the ears of dolphins and whales are shielded to protect them. Pictured are spinner dolphins, whose echolocation clicks can range up to 65 kHz and travel 200 m (657 ft).

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Navigation technique -

Amazon river dolphins put their sonar to particular good use, often employing echolocation to navigate around tree branches and other debris created by seasonal flooding.

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Range finding -

Using echolocation, dolphins can detect an object the size of a small apple about the length of a football pitch away. And very cleverly, dolphins move their heads to aim the sound beam at different parts of a fish to differentiate between species.

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Hi-Fi -

Similar is appearance to dolphins, porpoises are in fact more closely related to narwhals and belugas. These mammals also have a high frequency range of about 130 kHz. Pictured is a Yangtze finless porpoise, classified as Critically Endangered by the International Union for Conservation of Nature (IUCN).

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Isolating objects -

One of the smallest species of cetacean, the harbour porpoise is armed with a very high-frequency bisonar, which means that the sound beam they project while echolocating is narrow enough to isolate echoes from much smaller objects.

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Twittering -

Native to Madagascar, the tenrec primarily uses touch and scent to communicate. But this close relative of the mole and shrew is also believed to use twittering vocalizations to echolocate.

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"Echo-orientation" -

Shrews, meanwhile, have been found using high pitched twittering vocalizations to echolocate their surroundings. This has been described by some scientists as "echo-orientation" or "echo-navigation."

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Tree sonar -

The dormouse is the only tree-climbing mammal known to use ultrasonic echolocation. The Vietnamese pygmy dormouse, for example, has developed a biological sonar that rivals the likes of echolocating aficionados like bats and dolphins. Pictured is the garden dormouse.

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Hearing to see -

The aye-aye, a species of lemur endemic to Madagascar, is the world's largest nocturnal primate. It uses its bat-like ears for echolocation.

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Whistling to communicate -

While it's not yet scientifically proven, the humble hedgehog may echolocate. It certainly uses ultrasonic whistles to communicate, and they have excellent hearing.

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A rare talent -

Echolocation in birds is extremely rare. But there are some that do employ bisonar. One such species is the South American oilbird. Known also as the guacharo, it uses its admittedly rudimentary echolocating talent to navigate the dark environments of the caves its roosts in.

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Click to send -

Another cave-dwelling bird, the swiftlet uses its specialized vocal organs to produce both single clicks and double clicks for echolocation. There are around 16 species of swiftlet known to echolocate. Pictured is the Himalayan swiftlet.

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Sight and sound -

And yes, even we can use echolocation. Most humans who echolocate are blind or vision-impaired and use the skill to go about their daily activities. Blind people often use short and quick cane taps to echolocate. In fact, echolocation can be so precise that they can distinguish textures such as metal through sound.

Sources: (Scientific American) (ScienceDaily) (IUCN) (Smithsonian Magazine) (Science)

See also: The secret life of bats

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