Concave ear frogs call their partners with ultrasound

Most female frogs do not call their partners, because they do not have vocal cords or their vocal cords. A female chooses a partner from a male choir and quietly gestures to the guy.

But the female frogs live in the rough waters, Odorrana tormota, there is another way to express their interests: It emits a high-pitched chirp that our human ears sound like. birds singing. This is one of the unusual frog-related findings published in this week's issue of Nature.

O.tormota frog lives in a noisy environment, in dense bushes on the banks of Huangshan Hot Spring - the center of China, where waterfalls and currents make noise noises. stop. The frog has a deep eardrum, Albert Feng, a professor of molecular and extended physiology at University University, and leader of the research group.

Feng said: 'In the world, we know two concave ear frogs - another concave ear frog in Southeast Asia - with concave-shaped concave ears. Other species have eardrums on the surface of the body. '

O.tormota frog lives in a noisy environment, in dense bushes on the banks of Huangshan Hot Spring - the center of China, where waterfalls and currents make noise noises. stop.(Photo: Albert Feng)

Previous studies - conducted by Feng, Jun-Xian Shen at the Biophysical Academy of the Chinese Academy of Sciences and Peter Narins at the University of California, Los Angeles - discovered O. tormota males and responding to unusual chirping sounds from other males. These sounds can be heard, these also have ultrasonic energy. Deep eardrum structure, about one-third the thickness of regular frogs, allows them to hear high-frequency sounds.

Feng said unusual ear structures and high-pitched calls are likely to evolve to adapt to a noisy environment. Waterfalls and streams create regular noises that are mostly lower in frequency than the frogs emit.

The experiment showed that other frogs could hear most types of sounds, including sounds with ultrasonic frequencies emitted by O. tormota frogs. Other animals also use ultrasonic waves to communicate such as bats, dolphins, whales and some insects.

These calls are quite complicated. An O.tormota frog transmits its message at several different frequencies at the same time, with time between the sounds, like a chord being plowed at the same time on multiple strings.

Shen, Feng and Narins analyzed and found that the O. tormota female frog emitted a sound that came from the audible frequency and the ultrasonic frequency. The team has not observed female frogs producing such sounds in nature (O. tormota frogs that are nocturnal can jump as much as 30 times their body length), but in laboratory conditions. They only emit these sounds while carrying eggs.

Male O. tormota are told to respond to the calls of female children that respond quite responsibly, often chirping within a fraction of a second.

"The reaction of the males is instantaneous - right after the stimulus," Feng said . In the laboratory, the males often chirp and jump straight to the area where the children call. Feng realized that their ability to find a place to call was amazingly accurate. A male can jump to a place with a call with accuracy of more than 99%.

He said: 'This has never been known in the frog kingdom.'

Only elephants, humans, pig birds and dolphins are known for their ability to detect similar sounds. Feng said that the distance between the short ears makes the frog's ability to sound sound even more impressive.
But the way that children choose their partners in nature is still a mystery.

Feng said: ' We still have a lot of work to do to find out whether children directly signal a male or it signals a group of males to come and compete, or have a duet form. Then the children decided: 'Okay, I'm my boy. Jump on my back and I'll take you to the creek! '

Research is also relevant to human health. A previous study of frog listening and hearing mechanisms helped Feng and his colleagues (U. of I.'s Beckman Advanced Science and Technology Institute) design a hearing aid 'through Can ' raise the signal of excitement associated with other sounds in the audience's direct environment.