August 29, 2008

Flies: More than Meets the Eye

Ever feel the frustration of failing to swat a fly? Well, researchers say they've solved the mystery.

A U.S.-based study found the fly's ability to stay alive is due to its fast acting brain and an uncanny ability to plan ahead.

The research noted that at the faintest hint of a threat, the insects adjust their preflight stance to flee in the opposite direction, ensuring a clean getaway. The study said this explains why flies so easily evade swipes from their human foes.

"These movements are made very rapidly, within about 200 milliseconds, but within that time the animal determines where the threat is coming from and activates an appropriate set of movements to position its legs and wings," said Michael Dickinson of the California Institute of Technology.

The research suggests that the best way of swatting a fly is to creep up slowly and aim ahead of its location.

The study has been published in the journal Current Biology.

Researchers used high-speed digital imaging equipment and a fancy fly swatter. They found in response to a threat from the front, the fly moves its middle legs forward, leans back and raises its back legs for a backward takeoff. And if the incoming threat is from the side, the fly leans the other way before takeoff.

"It is best not to swat at the fly's starting position," Dickinson said. Instead, aim for the escape route.

Dickinson, a bioengineer, has spent his life studying the insect in flight. He built a small robotic fly named Robofly and a 3-D visual flight simulator called Fly-O-Vision.

The study found flies position their bodies into pre-flight mode very quickly. The scientists discovered flies were able to put themselves into this rapid reaction position no matter whether they were grooming, feeding or simply walking.

Dickinson said this illustrates the speed and complexity of the fly's brain.

"We've found that when the fly makes planning movements prior to take-off, it takes into account its body position at the time it first sees the threat," he explained.

"Our experiments showed that the fly somehow 'knows' whether it needs to make large or small postural changes."

Dickinson emphasized the importance of advances in high-speed imaging for making such discoveries possible.

"These instruments have done for the time domain what the electron microscope did for space," he said. "As these instruments become more common, I think we will see that animals perform many behaviors on rapid time scales that simply evaded the detection of our sluggish eyes."

He also hopes the findings in flies will give people a greater appreciation for the insects, and make them "think before they swat."


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