Two centuries ago, a doctor from Geneva, Jurine, published the results of his unusual experiments.
A researcher found that bats, possessing outstanding abilities to navigate in the dark (this amazing trait was known long before Jurine), became completely helpless if their... ears were blocked with cotton. Jurine suggested that hearing replaces vision for bats.
Later, this hypothesis was confirmed by the Italian Spallanzani, who conducted a series of similar experiments. But how does this creature perceive silent objects? One of the scientists interested in why a bat emits a constant squeak during flight decided to block its mouth instead of its ears. And what happened? The creature again seemed to lose its sight... Thus, it was discovered that the squeak serves as a “guide” for bats: by capturing the echoes reflected from various objects, the creature accurately determines their location in space and easily finds its way, even without the aid of sight. It seemed that the mystery was solved.
However... Scientists determined the range of sound waves that bats “use.” The minimum wavelength of their “sonar” was about four millimeters. It is known that sound waves can only be reflected from objects that are at least half the length of these waves. Therefore, theoretically, bats could only detect objects in space that are no smaller than two millimeters.
However, recent studies have shown that bats “noticed” much smaller objects. Researchers trained them to respond to a specific sound signaling feeding time, to fly into a darkened room where one of the laboratory staff held a millimeter worm with extended tweezers. Not a single bat missed even once...
The experiment was complicated. A nylon mesh with thin, barely visible threads — up to eight hundredths of a millimeter — was inserted into the door separating two rooms. And what happened? Flying through the cells of this almost invisible mesh, not a single bat touched even the thinnest thread. Thus, an interesting fact was established — the ability to “see” objects using ultrasound turned out to be 25 times greater for bats than the “calculated” ability.
So what is the matter? How does the ultrasonic orientation mechanism of bats function?
...One of the scientists participating in the new series of experiments with bats noted: “It is still unclear what the exact answer to these questions will be. But one thing is obvious — there is much for bionics specialists to learn here...”
