Handout 5-C

Communication and Echolocation in Marine Mammals

How do dolphins communicate?

Dolphins make a wide array of sounds, including clicks, moans, chirps,creaks, barks, squeaks, yaps, mews, and whistles. They are also excellent mimics and have been known to makes sounds resembling the engine of a motorboat, the laugh of their trainer, and the brrrr of a Bronx cheer!

Dolphins use clicking noises in echolocation (CCRClink), which bounce off objects underwater. This allows them to navigate, identify prey and friends, and avoid obstacles and predators. Dolphins use whistles to maintain contact within their pod or when meeting other pods of dolphins. Their whistles may signal danger, a call for help, or simply identification. Scientists think that each dolphin has its own signature whistle, sort of like our names. Whistles may also help dolphins hunt cooperatively and coordinate migratory movements.

Do dolphins have their own language?

For many years, people have been trying to understand if the rich variety of sounds produced by dolphins could be a coded, secret "language." Louis Hermann of the University of Hawaii's Kewalo Basin Marine Mammal Lab is a leader in the field of animal-language research. He does not believe dolphins have their own language, but he has been able to teach artificial language to four dolphins at his lab. He uses two approaches: sight and sound. With one dolphin he uses hand signals to give instructions to fetch a ball or play Simon Says. With another, he communicates using different tones of electronic whistles.

How do scientists study marine mammals' use of sound in social interactions?

Sounds (Sound links) carry a long distance underwater, but we humans, at least, have a hard time pinpointing where the sounds originate. Scientists recording the sounds of captive dolphins often found it impossible to decipher which animals was making which sounds, since marine mammals do not move their mouths when they vocalize.

Peter Tyack, a whale researcher at the Woods Hole Oceanographic Institution, has developed the "datalogger," a computerized instrument designed to record sounds made by captive marine mammals, such as beluga whales and dolphins. Each datalogger contains an underwater microphone linked to a small computer to store information. A datalogger is attached to a subject's back by two suction cups. As the animals vocalize, the datalogger on each animal picks up the loudest sound, revealing who is "talking."

(The Center for Cetacean Research & Conservation - CCRC Home)

http://www.gma.org/marinemammals/profiles.html

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