Robotic frogs made with condoms
In "The frog robot condom," The Scientist invites us to follow Peter Narins, a professor at the University of California, Los Angeles (UCLA). He has already been on 42 field expeditions, tracking the vocal behavior of animals in their natural habitats. But his most interesting research work has been done with frogs. Since 2001, in places such as China, French Guiana or Puerto Rico, he has been using robotic frogs housing a speaker and an air pump. But the air pump, used to call or to ask other frogs to leave, inflates and deflates the robotic frog's throat sac, made from a condom. Next year, Narins will go to Brunei to study another kind of frog. But he will use enhanced versions of his robots which will be equipped with several motors.
Here is the introduction of the article from The Scientist.
Peter Narins needed a way to convince real frogs that a male intruder has just hopped into their territory and is croaking boldly. So the animal communication researcher came up with the obvious choice: condoms. In 2000, Narins, a professor at the University of California, Los Angeles, and his colleagues at the University of Vienna glued a condom to the jaw of a robotic frog equipped with an air pump and speaker. It worked: The condom makes such a believable vocal sac that the robot, despite its immobility, can incite a real frog to spar.
Back in 2001, Susan Milius wrote an article about this specific project for Science News, "New robot frog gets into fights - robot frog is attacked by other frogs," which gives more details about this robotic frog called Roborana. (Rana means frog in Latin.)
This fake frog sits on what looks like a plain old log. However, the log houses a speaker and an air pump. From a hiding place, the researchers trigger broadcasts of a male's call. The air pump inflates and deflates Roborana's throat sac, made from a condom, in sync with the calls.
Adding the model with this sac makes a huge difference, Narins reports. Simply broadcasting the call has the usual effect of luring a male, but the puffing sac provokes attacks. He and his colleagues have videotaped a frog hopping over to Roborana, pouncing on top of the robot, and swiping at the vocal sac. With this new tool, Narins hopes to tease out more about how frogs interpret these signals.
Peter Narins, who works at the UCLA Department of Ecology and Evolutionary Biology, doesn't show many pictures of the robotic frogs he's using. But below is a picture of the "electromechanical frog (left) [used] in a field study in French Guiana to understand the cues that evoke aggressive behavior in a dendrobatid frog (right). (Credit: Peter Narins's research group at UCLA).
Narins returned to China several years later and you can read that "Rare Chinese frogs communicate by means of ultrasonic sound" (UIUC, March 15, 2006) or that "Scientists Discover Why Chinese Frog Has Ear Canal" (UCLA, March 28, 2006).
But let's return to The Scientist to discover the next robotic frogs which will move to Brunei next year.
In August 2007 Narins will embark on a field expedition to study a different species, one he expects to be less focused on condoms and more interested in legs. Staurois natator, the black-spotted rock frog, lives near loud, fast-running streams in forests, and Narins thinks it's unlikely the animals make vocal calls over the din. Rather, he suspects the frogs' communication relies on a graceful movement called foot flagging, where the frog stretches out its rear leg and slowly rotates it in the air. Instead of an inflatable vocal sac, "robo-staurois" will have three miniature motors (each measuring 2x6 mm) to mimic and modify foot-flagging motions, so Narins and colleagues can see what signals frogs respond to in the field.
I sure hope that this next expedition goes well. Wouldn't you like to have a science professor such as Narins to talk about nature to your children?
Sources: Kerry Grens, The Scientist, Volume 20, Issue 12, Page 18, December 1, 2006; and various websites
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