The calls are quite complex. A single O. tormota frog broadcasts its message over several frequencies at once, at harmonic intervals, like a chord strummed simultaneously on several strings.
The new analysis, conducted by Shen, Feng and Narins, found that female O. tormota frogs also emit a call that spans audible and ultrasonic frequencies. The team has not observed females vocalizing in the wild (these frogs are nocturnal and can leap up to 30 times their body length), but in laboratory settings the females emitted calls only when they were carrying eggs.
Male O. tormota frogs exposed to recorded female calls were quite responsive, usually chirping within a small fraction of a second.
The frogs response is instantaneous right after the stimulus, Feng said.
In the laboratory, the males usually chirped and then leapt directly at the source of the female call. Their ability to home in on the sound call was astonishingly precise, Feng said. A typical male could leap toward the sound with an accuracy of over 99 percent.
This is just unheard of in the frog kingdom, he said.
Only elephants, humans, barn owls and dolphins are known to detect sound with similar precision. The small distance between the frogs ears (about one centimeter) makes its ability to localize the sound that much more impressive, Feng said.
How the female picks a mate in the wild is still unknown, however.
We have a lot of work to do to figure out whether she directs the signal to one male or whether she lets a bunch of males come and compete, or whether there is any kind of dueting session during which she then decides: OK, Youre my guy. Hop on my back and Ill take you to the creek! Feng said.
These studies likely have implications for human health. Earlier research into the mechanics of frog hearing and directional hearing helped Feng and his colleagues at the U. of I
|Contact: Diana Yates|
University of Illinois at Urbana-Champaign