Monday, January 11, 2010

Sonar wars in the night skies

When the idea struck him, he had already spent a decade studying moths' sound-producing structures, called tymbal organs, and how moths use sound to communicate with one another in courtship. From there, it was natural to ease into moths' communication with their predators.

Conner began to study bats and moths together and learned that just like military aircraft, at least one species of tiger moth can jam enemy sonar by producing a sound at the right frequency. Moths, of course, found it first.

Jamming sonar means the moths interfere with their enemies' fine-tuned way of bouncing sound off objects to navigate. However, the B. trigona moth seems to thwart its enemy, the bat, every time, and the military still can't claim that rate for foiling anti-aircraft missiles. Conner has only studied the one type of moth but has never seen a moth get eaten after producing the high frequency racket. So can the military learn a thing or two from a moth?

Maybe so, says Conner. He and graduate student Aaron Corcoran study how the signals produced by bats and moths have evolved, and by turns eclipsed each other, throughout their predator/prey history. For now, this steely grey tiger moth - dappled with orange to befit its name - has the advantage. While the military toys with one frequency or another in electronic jamming, the tiger moth easily sounds just the right frequency or mix of frequencies to avoid the bat's jaws.

"This is the first incidence of prey jamming a predator's sonar," said Corcoran. "There are a number of parallels to human military strategies. These animals have likely been using this strategy for millions of years, predating human technologies." The study was published recently in the journal Science.

After time spent in Wake Forest University bat facilities, the team has determined that the moth isn't simply warning the bat away or startling the bat out of a meal. No, they think the moth's distinctive ultrasonic clicking, which sounds to the human ear like the quick back-and-forth wiggling of a zipper, causes the bat to hear double or interrupted echoes when trying to locate prey. Ultimately, this means miscalculating the moth's location and losing the snack. But the team still really doesn't know how the clicking works.

Steve Nowicki, a Duke University animal communication expert who is not involved in the study, says that grasping how conversation systems work within and without a species, from the inch-long tiger moth to the flat-faced bat, is important for more than military technology.

"Communication is fundamentally a biological problem. By understanding how animals communicate, we might get some glimpses into the origin of our own language and therefore what it means to be human," Nowicki said.


Another interesting science article from today: Self-cloning tree is 13,000 years old