Blessed with the power of echolocation reflected sound bats rule the night skies. There are more than 1,000 species of these echolocating night creatures, compared with just 80 species of non-echolocating nocturnal birds. And while it seems that echolocation works together with normal vision to give bats an evolutionary edge, nobody knows exactly how.
Now Dr. Arjan Boonman and Dr. Yossi Yovel of Tel Aviv University's Department of Zoology suggest that bats use vision to keep track of where they're going and echolocation to hunt tiny insects that most nocturnal predators can't see. The findings, published in Frontiers in Physiology, add to our scientific understanding of sensory evolution.
"Imagine driving down the highway: Everything is clear in the distance, but objects are a blur when you pass them," said Dr. Boonman. "Well, echolocation gives bats the unique ability to home in on small objects mostly insects while flying at high speeds."
Battle of the senses
Bats do most of their feeding at dusk, when insects are most active and there is still plenty of light. Under these conditions, vision seems a better option than echolocation it conveys more information, and more quickly, at a higher resolution. The researchers wondered: If bats evolved vision before echolocation, as scientists believe, why did echolocation ever come along?
The team set out to answer this question by comparing the distances at which the two senses can detect small objects. To estimate the range of ultrasonic bat echolocation, the researchers played taped calls of two species of bats in a soundproof room and recorded the way the sound bounced off four dead insects a moth, an ant, a lacewing, and a mosquito. Vision is hard to simulate, so, extrapolating from the findings of two previous studies, the researchers calculated the distance at which bats would be able to see the same insects in medium to low light.
|Contact: George Hunka|
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