Scientists have been puzzled over the purpose of the Tiger Moth's tymbal organ membrane, which is able to vibrate at ultrasonic frequencies. The consensus is that it serves as a warning to bats, since the moths are able to retain poisons harvested from host plants. Scientists believed the moths who were poisonous were warning the bats, and those that weren't were faking it anyways.
New experiments by Aaron Corcoran of Wake Forest University, however, have confirmed another theory: the moths are actually using the fast paced clicking to jam the bats' echolocation. It is the first evidence of sonar jamming in nature:
New experiments by Aaron Corcoran of Wake Forest University, however, have confirmed another theory: the moths are actually using the fast paced clicking to jam the bats' echolocation. It is the first evidence of sonar jamming in nature:
Normally, a bat attack starts with relatively intermittent sounds. They then increase in frequency—up to 200 cries per second—as the bat gets closer to the moth "so it knows where the moth is at that critical moment," Corcoran explains. But his research showed that just as bats were increasing their click frequency, moths "turn on sound production full blast," clicking at a rate of up to 4,500 times a second. This furious clicking by the moths reversed the bats' pattern—the frequency of bat sonar decreased, rather than increased, as it approached its prey, suggesting that it lost its target.
From the Upcoming ueue, submitted by coconutnut.
Things don't evolve for specific purposes... they randomly mutate a trait, and if the trait aids survival and/or reporduction (which is a subset of survival), the trait becomes more wisespread.
So.. in this case, the moths didn't really 'evolve to trick bats', but rather, some evolved a trait that happened to trick bat (which aided the propagation of that trait.)
The effect is the same, but what is important in undestanding Darwinism is that the evolution of a trait isn't... intentional (or reactionary for that matter). Its random mutation, propogated and/or culled by how that mutation aids or hinders the species.
http://www.youtube.com/watch?v=vrZ2hNZsCuE&feature=channel