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Animal Sonar - Beginnings
by BiologyofNature.net
Some of the biggest noise makers of the animal world are fish and marine animals. Scientists can put microphones into the sea and receive a racket that is often worse than a high school band playing off key. The sounds are in the form of barks, groans, whistles, and other similar noises.
The toadfish has a simple underwater sound compared to a human voice. A goby fish was taped by a scientist replaying the sounds when underwater that suddenly had a school of goby fish flocking to his sight. The sea croaker has a sound similar to the earliest machine guns, which is rat-a-tat-tat. This may be the reason for the slang words "gattlin guns," etc.
The coast defense stations of the United States had been protected with explosive mines during World War II. These mines often exploded without the threat of a nearby enemy submarine, but wherein did the fault lie? Scientists discovered that the little toadfish conversationalists set off the mines, as well as the snapping of shrimp. Fortunately, the United States Navy has researched this problem and are attempting to control interference from the conversations of all ocean fish.
Not to be out done, many land animals have this conversational ability. A farmer reported the trapping of a king rat in his barn. The king rat kept squealing, which warned away any other adventurous king rat. Is this the infallible mouse trap? It was discovered that a tape recording had the same effect and would frighten away squirrels and mice as well.
It was an Italian scientist living over 200 years ago who discovered the ability of bats to find food without sight or smell. He decided to keep track of the insects considered most edible by the bat community. He would release blind bats in a room and observe the way they avoided colliding into objects, which were directly in their path. He then let the bats fly outdoors. Once the bats returned home the scientist discovered fresh insects in the digestive system. It was obvious the bats used something other than eyes, but at that time sonar was unknown.
American scientists began solving the puzzle some years ago. The experiments included checking the ability of bats to fly around blindfolded compared to being able to see. The next step was to cover the ear of some of the bats. This proved a vital point: the bats did not want to fly, and when they did, they were bumping into things. It was clear that sound played a major role in the ability of the bats to locate food and avoid objects.
It was suggested that the bats themselves made sounds that were reflected back from any nearby objects, just like sonar. Researchers then covered the nose and mouth of a bat, but left its ears free. The result was the same: it did not want to fly, but when it did, it kept bumping into things. This provided researchers with enough information to prove that bats make sounds that are used as sonar. Once equipment was invented to record the sound, it turned out to be a series of sharp, ultrasonic squeaking waves. The sound frequencies went as high as 50,000, and the vibrations reached about 5,000 per second.
Later experiments showed that bats are able to recognize their own sound and completely ignore the sounds produced by other bats. Bat sonar is so sensitive that a bat can find his way in a dark room with fine wires stretched across the room.
Another sea animal that uses sonar is the porpoise. It is so adept that it can distinguish between two kinds of fish underwater. The porpoise is believed to have a sonar better than any built by man thus far. Researchers are still studying ways to make their sonar as effective and accurate as the porpoise. Porpoises have another talent-they are able to imitate some sounds of human speech. Maybe we will discover how we sound to the other animals.
Birds are believed to use their singing, or musical voices, not only for communication, but also just for fun. A bird has its own true song, but also has a song that it will use to warn other birds of an enemy. Young birds have a baby talk song mixed with a variety of other sounds. As with human babies, the young birds drop the sounds that are not used by the grown-ups.
The electronic evolution continues with the ability to record and study the sounds used by the animals of the world to communicate, with one another and, maybe, eventually with mankind.
Source:
1. Editors. The World Book Encyclopedia. World Book-Childcraft International, Inc: Chicago. 1990
Further Study:
Animal Sonar
There are many types of sonar in the world. However, mother nature has once again showed us the way to show how to make sonar help us.
Navy's Sonar Program Turns Deaf Ear to Whales' Welfare
The U.S. Navy and animal activists are squaring off over a new sonar system that could have deadly consequences for whales.
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