Deaf Manatees

Podcast

Deaf Manatees

Transcript

Scientists find that manatees are deaf, not dumb. I'm Bob Hirshon, and this is Science Update.

One of Florida's most famous and most homely animals is the manatee,or sea cow. These lumbering cousins of elephants look slow, but they can actually zip around in the water at a rate of twenty feet per second. Yet they're often maimed, and sometimes killed, by speedboats.

Scientists thought that maybe sea cows just didn't have the smarts to stay away from boats. But Edmund Gerstein (ger-steen) of Florida Atlantic University says that the sea cows aren't stupid. They just don't hear the boats coming. He conducted the first ever manatee hearing tests.

Gerstein:
"The animals were basically trained to push on one paddle if they didn't hear something and push on another if they did. And they'd get rewarded with something that they like. If they didn't get it correctly, they would never receive any kind of punishment or anything. What would happen is they would simply be sent to do the next trial. It turns out that manatees have much higher frequency hearing than was previously thought. But unfortunately for them, boats put out primarily low frequency sounds."

He says that explains why boats that slow down for manatees actually hit more of them. To fix the problem, Dr. Gerstein is developing a "warning beacon" for boats that sends out a signal manatees can hear. He hopes that if the manatees can hear the boats coming, they'll have time to get out of harm's way.

For the American Association for the Advancement of Science, I'm Bob Hirshon.