Porpoise 'Pings' in on target

Title

Identifier

Sound off!

Language

English

Source

Panorama Volume XII (No. 2) February 1960

Year

1960

Rights

In Copyright - Educational Use Permitted

Fulltext

Sound off! Porpoise 'Pings’ in on Target The porpoise apparently lo cates fish and objects in the water in much the same manner that a destroyer “pings” in on an enemy submarine. The porpoise’s sight-by-sound process is based on the same prin ciple used by Navy sonar or ma rine fathometers for locating un derwater objects, by sending out a series of noises and then pick ing up the reflected echoes. For “auditory glances” the por poise sends out a series of sound pulses. The experiments proved that the porpoise has a supersensi tive auditory mechanism for pick ing up any reflected noises. So sensitive is the porpoise’s auditory system that it can hear a single BB shot dropped into the water or a half teaspoonful of wa ter dropped from a height of five or six feet, Dr. Kellogg reports. The experiments showed that the porpoise is capable of reacting to sound vibrations in water at least as high in frequency as eighty kilocycles a second—or two full octaves above the hearing threshhold for man. y N THE EXPERIMENTS, an object, such as a fish, was dropped into the water. The noise of the splash provoked “a torrent of sput tering sound pulses” as the por poise dashed toward the target. When the object was lowered quietly into the water, there might be a delay of ten or fifteen min utes before the porpoise spotted it with random “auditory glances.” The experiments also established that the porpoise uses its echo ranging system for avoiding colli sions with underwater objects. By a series of experiments, the scientists ruled out the possibili ties that the porpoises were as sisted in their underwater detec tion by sight, smell, temperature or touch. The experiments, for instance, were conducted in murky water or in the dark of night, but still the porpoise was able to swim through a maze of underwater ob jects to home in on targets. It also proved capable of avoiding solid but invisible objects such as a glass door. The experiments, supported in 66 Panorama part by grants from the National Science Foundation, were con ducted with two shallow-water porpoises, or bottlenose dolphins, donated by the Marine Studios of Marineland Florida. The porpoise is one of the smaller of the toothed whales, and thus is related to the giant sperm whale. The porpoises, known for their playfulness and intelligence, prov ed to be reluctant subjects. The young male dolphin "appeared to be quite dependent upon the more mature female dolphin and swam immediately to her side in times of stress or excitement,” the re port said. The female dolphin, in turn, "displayed a certain reserve or sophistication by withdrawing, of her own choice, from participa tion” in two of the major experi ments. To Thy Kingdom Come “Pilot to tower, pilot to tower: plane out of gas; am one thousand feet and thirty miles over the ocean, what will I do?" “Tower to pilot, tower to pilot: repeat after me —Our father who art in heaven . . .” if * * It's in the Drawer! “Fasten your seat belt, please," said the stewar dess, as they were about to take off. “Oh, dear!" cried the woman. “I didn’t even bring one!" * ¥ if What's in a Name? “Why did Friday wake up at dawn every morn ing?" “Because Robinson crew so" if February 1960 67

pages

66+

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