Air Date: Week of March 15, 2002

Living on Earth's Maggie Villiger reports on how their lungs help some reptiles and amphibians hear.

Transcript

CURWOOD: Just ahead, a world update from Mark Hertsgaard. First, this page from the Animal Notebook with Maggie Villiger.

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VILLIGER: Lizard lips may be nothing to sing about, but you might want to strike up the band for lizard lungs. Scientists say that salamanders and lizards, along with snakes and frogs, use their lungs to help them hear. These reptiles and amphibians lack eardrums and other middle ear elements that normally channel sound wave vibrations to the inner ear. But judging from their behavior, these animals can sense sound. To figure out how, researchers shot sound waves at different parts of the lizards' bodies. They found that the section of body wall that covers the lungs vibrated strongly. To make sure that it was this air filled cavity that was the key to the vibrating phenomenon, and not the body wall itself, the scientists filled the lungs with an oxygenated saline solution. The lizards could still breathe, but sound waves produced vibrations of only about a tenth the original size. Researchers think the sounds create pressure waves in the lungs that then travel on to the inner ear where they are detected as sound. The process may be an evolutionary leftover from the aquatic ancestors of terrestrial vertebrates, back before land-dwellers grew ears like ours.
That's this week's Animal Note. I'm Maggie Villiger.

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CURWOOD: And you're listening to Living on Earth.

[MUSIC: Zubot & Dawson, "Fried Chicken Head," TRACTOR PARTS (Black Hen Music - 2000)]