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Science Frontiers ONLINE No. 119: Sep-Oct 1998 |
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Mapping With A Song
The songs of the humpback whale are complex and eerily melodic. Only the male humpbacks sing, and then only during the mating season. In contrast, the songs of blue whales are exceedingly dull. They consist of only five notes repeated in various combinations. Since both sexes sing most of the year, the songs of the blue whale probably have nothing to do with reproduction. Then, why do they sing?
A clue to the purpose of the blue whales' songs is found in their precision timing. One note is sung every 128 seconds. Furthermore, these notes (sound pulses) carry for hundreds of kilometers. C. Clark, a Cornell scientist, believes these notes are really sonar pulses used for fixing a whale's location. Echoes returned from distant seamounts, continental shelves, and other undersea topography enable the whales to map their positions within the wide ocean basins as they wander far and wide.
(Hecht, Jeff; "Rhythm of Blues Charts the Ocean Depths," New Scientist, p. 19, June 20, 1998.)
Comment. Short-range sonar is widely used by bats, Oilbirds, Edible-nest Swifts, and, of course, dolphins. As far as we know, the blue whale is the only animal employing sonar for longrange mapping. However, some birds seem to use distant infrasound sources (ocean surf, wind flowing over mountain ranges, etc.) as crude beacons during migration.