Beluga Whales: Sea Canaries

(Excerpted from Creatures of the Sea, published by KidHaven Press and available online in Kids InfoBits)

Belugas are among the most vocal of all whales. They constantly make loud noises that can be heard through the hulls of ships or even out of the water.

These noises change from moment to moment and sometimes even sound like songs. Because of this trait, beluga whales are often called "sea canaries." Their singing has delighted sailors since the earliest days of human sea travel.

Today, scientists use waterproof microphones called hydrophones to listen to beluga whales as they chatter in their underwater homes. Hydrophones let scientists hear whales that are far away. They also allow scientists to record beluga songs and study them later. By doing this, scientists hope to learn more about beluga whales.

The Singing Beluga

Belugas can make many sounds. Their calls have been described as barks, chirps, gurgles, grunts, groans, mews, moos, squeaks, trills, whistles, and yaps.

Different sounds seem to be used in different situations. Squawks and buzzing noises, for instance, are used mostly during socializing. Sharp grunts are used by mother belugas to warn their calves of danger. The calves respond with whistles. A sharp bang that sounds a little like a human hand clap is an aggressive noise meant to startle other animals. And trilling noises may be used to coordinate movements among a group of belugas.

Besides their natural sounds, beluga whales can also imitate the sounds made by people and other animals. They are very good at this. A beluga whale named Logosi who lived at the Vancouver Aquarium in Canada even learned to say his own name.

Beluga whales respond to each other's noises, so the beluga's song is definitely a form of communication. It is not a language in the human sense, however.

Belugas are not using words when they sing to each other. Rather, they are using different sounds to communicate information about their location, mood, and other general concepts.

Making the Sounds

Beluga whales do not have vocal cords, as most mammals do. Instead, they create their songs by moving air between sacs near the blowhole. As the air moves from sac to sac, it is forced through the "lips" of the sacs. The air vibrates the lips as it passes, and these vibrations produce noise. The lips can open and close to change the type of vibrations--and therefore noises--that are being produced.

Once vibrations have been produced, they pass through an organ called the melon. The melon, located inside the beluga's head, is a fatty ball that contains oils of different thicknesses. It is this organ that gives the beluga's forehead its rounded appearance.

As it makes sounds, a beluga whale uses muscles in its head to change the shape of the melon. Doing this changes the oils a noise must pass through. It also changes the melon's thickness. Both of these changes affect the noise being made. A beluga has excellent control over its melon and can make tiny changes to fine-tune its vocalizations. This skill lets beluga whales make the enormous variety of sounds for which they are known.

Changes in the melon can be seen from the outside of the body. When a beluga whale sings, its forehead constantly changes shape. These changes make the whale's face look unusually expressive.

Echolocation

Beluga whales use sound for more than just communication. They also use sound to find their way around and to locate objects. Using sound in this way is called echolocation. Echolocation is an ability the beluga shares with other toothed whales as well as some out-of-the-water creatures including bats, shrews, and some birds and insects.

To echolocate, a beluga whale produces a rapid series of clicks. The clicks pass through the melon, which focuses the sounds into a beam. The beluga shoots this sound beam forward into the water. The sounds bounce off objects in front of the beluga whale. Some of them are reflected back toward the beluga, which picks up the echoes with its lower jawbone. The echoes are then sent to the brain to be translated into information.

This translation is based on several things. The beluga's brain calculates how long the echo took to return. This tells the beluga how far away an object is. Tiny differences between the original calls and the way the echoes sound tell the whale about an object's shape and texture. Information about an object's size and movements can also be learned through echoes. Taken together, these pieces of information are so good that a beluga can probably "see" with sound nearly as well as a person can see with his or her eyes.