Name That Dolphin.
At an early age each dolphin adopts a personalized call--a unique whistle of rising and falling tones that emanates from nasal sacs below the blowhole (the single nostril atop a dolphin's head). Janik's computer analysis of 1,700 adult dolphin whistles reveals that dolphins separated by a distance of up to 599 meters (.36 miles) routinely imitate one another's signature calls--often repeating the exact whistle tones within seconds. Guess that's one way to find a pal in a giant pool!
How did Janik know he was hearing a true dolphin exchange? To count as a vocal match, each response had to occur within three seconds of the original call and originate from at least several meters away. Since sound moves faster under water (about 3,600 miles per hour) than dolphins can swim (18 to 25 mph), these rapid-fire exchanges must come from two individual dolphins, Janik concludes. "If you can copy another animal's signal, you can address that animal." Now if only he can figure out what dolphins gab about underwater!
* For more on how dolphins and other animals use sound for communication and navigation, see "Listening to Bats" on page 8.
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|Article Type:||Brief Article|
|Date:||Oct 16, 2000|
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