CommunicationMusic to swim by
Beneath the surface, where rays of sunlight cannot penetrate, the sea is the domain of obscurity. In this world, sound replaces light. One of the most impressive adaptations of whales is their ability to produce and perceive a very wide range of sound. The study of these sounds is key to understanding how whales live in this boundless, three-dimensional environment. Blue whales can produce very low frequency, omni-directional sounds inaudible to humans. These sounds can travel over hundreds of kilometres, however, no one knows for sure at what distance blue whales can effectively communicate. "Messages" could become transformed with distance making communication impossible beyond certain limits. Whales live on a different scale. To someone in an airplane, two fin whales several kilometres apart would naturally appear to be two lone individuals. In reality, these whales could be travelling together in a co-ordinated manner, continually exchanging information on the presence of food or boats.· Belugas and dolphins have incredibly varied vocal repertoires. But, as yet no one has been able to recognize any kind of language in these vocalizations. This diversity of sounds could be associated to their well-developed social behaviours. In the case of the beluga, which spends part of its time near ice floes that produce a very powerful background noise, the ability to emit a wide range of sounds is probably necessary to maintain contact between group members. Belugas and dolphins also use sound to "see" in the dark. By emitting a series of ultrasonic sounds directed with precision, they are able to navigate as bats do or like a ship captain using radar in fog. This system of echolocation allows them to determine the location, nature and movement of objects that would otherwise be invisible.
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