Echolocation and BioSonar

What is it?

Echolocation, also known as Bio-sonar , is an animal’s biological sonar that has adapted into an important use of the sense of hearing. Animals that Echolocate put out calls to the environment by creating sounds of various pitches. They then listen for the echoes that bounce off objects around them. The animal can then locate the nearby objects determining distance and proximity.

The animals that use Echolocation include bats, dolphins and whales, some birds, shrews and tenrecs , and maybe even humans! Donald Griffin, a professor of zoology, first coined the word “Echolocation.” In 1938, Griffin’s research combined with contributions from Robert Galambos , a Neuroscientist , concluded that bats utilize Echolocation. However, in the 18^th century, Lazzaro Spallanzani , an Italian scientist, had already discovered that bats use hearing for navigation rather than vision.

How does it Work?

First there must be vocalizations in the form of sound waves that are emitted. The ranging is performed by analyzing the time delay between the sound emission and the echoes that come back from the environment. The sound’s intensity that is received by each ear and the time delay provide information concerning the horizontal angle by which the sound waves arrive. The differences in loudness or decibel and time are utilized by animals to tell bo th distance as well as direction.

What is it used for?

Echolocation generally replaces the reliance of vision. Vision can be impaired by many reasons including lack of light, murky water, and poor sense of vision. Animals that rely on echolocation do so for navigating their environment and to forage for any available food. While these are the main reasons that animals use Echolocation, they also can use Echolocation for other reasons including basic as social interaction and orienting themselves in strange environments.

Although Echolocation has various benefits, it also has drawbacks. When hunting, the emitted sound alerts the prey to the presence of the hunter. When this happens, the prey exhibits defensive behaviors and may get away. Another possible occurrence is the pray creating defensive sounds which would interfere with the sound waves emitted by the hunter cutting of information retrieval thus making it essentially blind.

Who Uses Echolocation?

Bats

Bats are the most popular user of Echolocation. Bats create the sound in their larynx and emit it from their mouths and noses. The sound bounces off nearby objects and is received by bats noticeably large ears. Since bats live mostly in absolute darkness, they rely on echolocation for food and navigation. A bat can find out what is in its path, an object’s size, its direction, its shape, its motion and its distance.

Dolphins and Whales

Dolphins are another popular user of Echolocation. Dolphins create sound from lip-like membranes that sit near their blowholes. The audible sound is a series of various clicks. The tissues in the jawbones absorb the returning sound. Like bats, dolphins rely on Echolocation for a number of reasons including navigation and hunting, as well as, socialization and defense.

Whales use Echolocation much like Dolphins do. Whales make sounds from their cavities and larynx; a quick succession of clicks in a huge frequency range is produced. When the emitted sound bounces off of objects, it is received their lower jaws. From the lower jaw, the received sound is transferred to the ear. The main purpose of Echolocation for whales is to “see” the environment around them.

Birds

Birds, such as, swiftlets and oilbirds rely on a more primitive type of sonar than dolphins and bats. These birds make clicking sounds (sometimes single clicks, sometimes double clicks) while flying, and then receive the echos through their ears. For these birds, Echolocation is generally used to find nests in dark caves. Echolocation tells them exactly where to land and how far away their nests are.

Shrews and Tenrecs

Shrews and tenrecs are the only two terrestrial mammals that are known to depend on Echolocation. They produce ultrasonic squeaks that are much simpler than the sounds made by dolphins; they are merely frequency modulated and ultra-harmonic. Shrews and tenrecs rely on echolocation mainly to investigate their surroundings rather than hunting for food.

Can Humans use Echolocation?

Yes. Humans are also capable of using Echolocation. Generally, people with vision impairment are more likely to recieve benefits associted with Echolocation rather than a person with full vision capabilities. When a sense is disabled, other senses intensify to replace it. This creates a situation where a person is likely to succeed at learning and utilizing Echolocation. There are training classes that people can attend to learn this craft inspired by mentors in the animal kingdom. Basically, the person emits sound such as clicks, chirps, or even tapping a walking cane. Then the person listens to the echos and processes the information from the environment.

Another way people can utilize the benefits of Echolocation, is by using Sonar. Sonar was invented by scientists who were inspired by studying bats. The benefits of Sonar can be used in a variety of settings, such as, Submarine navigation and underwater location, mapping, medical situations, and many other uses.

For more information on Echolocation, see these links.

The Adventures of Echo the Bat

Kids Cave (Check out the Bat and Echolocation Video!)

Humans and Echolocation