Echolocation in Whales and Dolphins

How Marine Mammals Communicate and Navigate Underwater

Aug 14, 2009

Most people have heard CDs filled with whale sounds or songs. While it is a unique and relaxing sound, these chirps and clicks mean a lot more to whales than relaxation.

Whales and dolphins emit a variety of sounds in sequences of clicks, grunts, moans, squeals and chirps. Some whale squeals can last for 10 minutes and are quite high pitched. The use of these noises is called echolocation.

What is Echolocation?

Whales and dolphins communicate by using a method called echolocation. They emit clicks or chirps to help them locate food, to navigate underwater, and to communicate with each other. The echo bounces back off of an object and this tells the whale or dolphin things about the object such as size, distance away, and whether it is moving or not. Different whales use echolocation for different purposes.

When the sounds emitted bounce back from objects, it tells the sender information about that object. It allows for identification of friend, prey, predator or obstacle. Some whales and dolphins don’t use echolocation as a navigational tool and this explains how some whales collide with boats and some dolphins get caught in nets.

Echolocation also gives whales and dolphins information regarding water depth, shorelines and the sea floor. Sounds are usually emitted at a low frequency when the animal is swimming normally, however, it is thought that the sounds emitted at high intensity and frequency may actually stun or disorient prey.

How Echolocation Works

Whales can communicate over large distances at low frequency. Several kilometers in fact, and the sounds can travel at approximately 1.5 kilometers per second. That is around four and a half times faster then sounds traveling through air.

Whales make sounds by forcing the movement of air between their nasal sacs located in the blowhole. There is a tissue complex in the nasal region which is where sound is produced. This complex is called the dorsa bursa and contains ‘phonic lips’ which are small projections in the nasal passage.

Air passing through this tissue complex causes vibrations and produces sounds. Dolphins produce sound in a similar way by forcing the movement of air past nasal sacs located in the skull.

The frequency of a killer whale's sounds range between 0.5 – 40 KH2 and whale calves are able to vocalize just a few days after birth. A calf’s call will sound similar to the call of its mother.

Sonar Affect on Whale Echolocation

Humans use sonar (sound navigation and ranging) for a variety of purposes in the ocean. It is used in ships and boats to detect the depth of the water, to find fish, or to locate underwater objects. There is public concern for how sonar on ships and boats interferes with whale and dolphin echolocation and several scientists and governments aim to minimize the impacts from active sonar.

For more information or to listen to whale sounds go to Whales, Dolphins and Sound on the Australian Government Whale Conservation site, or visit the Killer Whales page on the Sea World site.

The copyright of the article Echolocation in Whales and Dolphins in Marine Mammals is owned by Roberta Goli. Permission to republish Echolocation in Whales and Dolphins in print or online must be granted by the author in writing.