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, 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 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."
Cheri Reechia, a graduate student at the Woods Hole Oceanographic Institution, is using the data logger to study vocalizations and social behavior among groups of beluga whales at four aquariums. Belugas long ago were nicknamed the "canaries of the sea" because sailors could hear their plaintive calls even through the wooden hulls of their sailing ships.
She believes understanding their vocal and social behavior will be helpful for captive-animal husbandry, perhaps providing information on changing social dynamics, breeding conditions, or the general health of captive belugas. Long-term, she hopes to use dataloggers to study wild beluga society, to track their movements and provide data for their protection in the ocean.
Do whales use echolocation all the time?
Whales and dolphins echolocate-emit clicking sounds that bounce off prey or objects in order to locate and identify them. Some scientists think that captive whales and dolphins do this much more than wild populations. Although all whales chatter up a storm to keep in contact with each other and to communicate (what, scientists don't know,) some whales may not use echolocation at all, but may find their prey simply by listening. The fact that sperm whales and right whales are struck by boats suggests they may not be using echolocation to avoid these large objects. Dolphins, too, may turn off their echolocation while traveling, which would explain why they become entangled in drift nets instead of leaping over them.
Scientists have determined that whales stay in touch with each other using a variety of vocalizations. Killer whales make plaintive, wailing noises. Fin whale pods typically have one whale that dominates the conversation while others take turns answering, according to Mark A. McDonald and colleagues at Scripps Institution of Oceanography. Blue whales, they found, call for 20 seconds, pause for 20 seconds, and then repeat the 20-second call.
As underwater noise pollution increases from boat engines, submarines, and oceanographic experiments, researchers feel it is critical to learn more about the way whales use sound in the wild in order to prevent human activities from disrupting the lives of cetaceans.
(Source: "Whale Chatter: Making sense of marine mammals' clicks and calls," Science News, May 25, 1996)