Caught! The Philippine tarsier (Tarsius syrichta) is the first documented example of primate that communicates with purely ultrasonic frequencies. Credit: David Haring
~ Becky Crew
Last week I was writing about how the Chinese concave-eared torrent frog can emit and perceive sounds at an ultrasonic frequency and my god, things got complicated.
In 2006, a team of scientists led by Albert S. Feng, a professor of molecular and integrative physiology at the University of Illinois, discovered that the concave-eared torrent frog, known for its ability to 'sing like a bird' and emit calls at ultrasonic frequencies, can also hear and respond to these calls. While humans can hear sound waves no higher than 20 kilohertz, some of these frogs' calls exceeded the researcher's recording device's maximum capability of 128 kilohertz.
Feng and colleagues suggested that this ability, which has not been found in any other frog species, was adapted to allow these extremely rare frogs to communicate over the constant noise of the waterfalls at Huangshan Hot Springs, west of Shanghai, where they live. "Nature has a way of evolving mechanisms to facilitate communication in very adverse situations," said Feng. "One of the ways is to shift the frequencies beyond the spectrum of the background noise."
And the only reason these frogs can hear themselves speak is that they are one of just two known species of frogs in the world that possess concave ears (the other is Borneo's wonderfully named hole-in-the-head frog.) While in most frog species the eardrum is external, concave-eared frogs have a recessed ear structure that protects an internal eardrum, which is about 1/30 the thickness of a normal frog's eardrum. The path between the concave-eared frog's eardrums and the ear is therefore shortened, which enables the transmission of ultrasound to the ears.
Two years later, the researchers came back with another discovery - the female concave-eared torrent frogs emit ultrasonic calls too, which is surprising because generally female frogs don't call. A female will usually sit back and listen to a chorus of males announcing their availability and silently signal the one she likes. Feng and colleagues admitted that they missed this the first time around because the females only emit ultrasonic calls when they are carrying eggs, so the chances of picking this up in the wild when they weren't expecting the females to be calling at all were pretty slim. In the lab, however, the females would call and the males, said to be quite responsive, would locate them, usually with an accuracy of 99%. "This is just unheard of in the frog kingdom," said Feng.
Now just when you think things couldn't get any more complicated, (each twist and turn kept the Playstation off and the heads of my Skyrim enemies still attached) the researchers arrived at yet another realisation .. http://www.cosmosmagazine.com/node/4416/full .. three years later. Unlike the male concave-eared frogs, the females do not have the ability to perceive ultrasonic calls. They literally can't hear themselves calling out to their mates, which means the males have an entire mode of communication all to themselves. It turns out that because the females typically hole themselves up in borrows and trees, away from the racket of the waterfalls that the wandering males have to contend with, their eardrums, while recessed, are not quite recessed enough.
This is the only example of a species of bird, mammal or amphibian where the males have an ultrasonic hearing capacity but the females don't, and we almost missed it because we just can't hear that well.
Yesterday scientists from the U.S. published a paper in Biology Letters .. http://www.cosmosmagazine.com/blog/5274/%3Cbr%20/%3Ehttp://www.cosmosmagazine.com/news/5267/endangered-primate-communicates-with-pure-ultrasound [dead] .. revealing that the tiny, endangered Philippine tarsier .. http://en.wikipedia.org/wiki/Philippine_tarsier ["threatened"] .. communicates through purely ultrasonic frequencies, and is the first primate known to do so. These demure, sweet-looking creatures were assumed to be one of the quietest species of primates, but the reality is they're probably screaming their heads off at each other and we had no idea. While it's sad to think we know this species - and likely many other species in the world - so, so little, it's a little bit thrilling knowing how much we have yet to discover about how animals communicate amongst themselves. As lead author of the tarsier study, Marissa Ramsier from Humboldt State University in California, said, "Many of my colleagues have noted silent mouth-opening behaviours in a wide range of species. There could be entire sets of signals out there waiting to be heard!"
gawd! .. the 'intelligent designer' really let female torrent frogs down .. hey!! .. with the virgin birth, et al .. evidence is building that discrimination against females started way way back .. then again it could be a plus for them .. no, it's just unfair .. lol
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