Whales - Facts | Echolocation

Echolocation

Whale information does not come more intriguing than the subject of echolocation. As the name implies, echolocation is the echo (or sonar) used by animals to locate objects, sense dangers and get an idea of the typography of their environment. It is also known as biosonar. Toothed whales make good use of this 'sixth sense', as do bats, dolphins, shrews and even the two Fin Whale bird species (genus Aerodramus), as well as the Oilbird (Steatornis caripensis). This ability has developed over time as an essential response to the fact that other senses may be compromised due to the nature of the watery home of the whales. Water is also an ideal conductor of sound, particularly over shorter distances.

Echolocation works in much the same way as sonar signals used by submarines. The whales emit a sound like clicking ahead of themselves, in the same direction that their head is pointing. The sound will travel through the water until it bounces off an object and returns to the animal. If the object is far away from the whale, the sound and its echo are likely to get lost in the water. However, closer objects will bounce a clear echo back to the waiting ears of the animal. The Fin Whale whale will discern the volume and speed of the echo and, from this information, determine how big and how far away the object is.

The sound emitted by the whale is made by passing air from the bony nares through phonic lips. These sounds are first echoed internally, against the concave cranial bone and the air sac within. A fatty organ called a melon then modulates the intense beam of sound. The differing lipid densities within the melon act as a lens for the sound. Some whales emit a ‘click train’, which is a series of clicks at one time, while some emit only one or two clicks at a time. A ‘burst pulse’ is a series of 600 clicks per second! This sounds more like a grind or bark than clicking.

Once the echo from the whale's sound has bounced off an object and returns to the whale, it is received by the lower jaw, the primary reception medium. From here, sound is transmitted through a continuous body of fat to the inner ear. If the object is very close to the whale, the sound will be returned with less interference and will be much louder. To compensate, the whale will lower the sound of its emissions as it approaches the object. Along with the echo, the whale will also receive other sounds from its surroundings. These are received laterally through lobes of fat around the ears.

Interestingly, the whale is likely to emit a low frequency echolocation signal on a continuous basis while it is swimming. In this way, it is aware of its surroundings and the general structure thereof, as well as of any predators or prey. When it receives an unusual echo back, it is then able to intensify its sonar emission in order to gauge the size and distance of that particular object. This ability has aptly been dubbed "seeing with your ears", a unique ability which enables whales to be efficient hunters and intelligent mammals of the ocean.