The Telltale Click

Heres a program from our archives.It’s well known that bats and dolphins use pulses of sound to echolocate. Now there’s evidence that yet another animal may have a built in sonar system – the hippopotamus. I’m Jim Metzner and this is the Pulse of the Planet.Ambience, Hippos Barklow: We found recently, through studies of blood proteins, molecular taxonomy, that hippos are the most closely related terrestrial organism to the whales and dolphins that is alive today.William Barklow is an associate professor in the department of biology at Framingham State College. On a recent trip to East Africa, he recorded a number of hippo vocalizations, and he found that the sounds are being transmitted both in the air and under water.Barklow: The common sound made by hippos, when you visit Africa, are referred to as a bellow. Also you hear in the background a lot of splashing and breathing. They expel air from their nose after a dive the same way that dolphins and whales do before taking the next breath.When Professor Barklow took the recordings of hippos bellowing and grunting, and slowed them down, he made an interesting discovery.Barklow: Those grunts are actually made up of individual, separate clicks that are repeated very quickly, like 30 times a second. Our ears are not good at resolving quick signals like that, so we hear it as a grunt. But in fact, every little sound of that grunt is an individual click. Those clicks are exciting because of the hippos supposed relation to the whales and dolphins. Dolphins, we know, echolocate using clicks. It is very possible that hippos also use click-trains underwater for echolocating. That’s something that we have to look into.Here’s a hippo’s grunt at normal speed… and now here’s the same sound slowed down, so that you can hear the clicks. This archival program is part of our thirtieth anniversary celebration. If you want hear more, check out our podcast.

The Telltale Click

Distant relatives of both dolphins and whales, hippos may also use sound to echolocate.
Air Date:09/25/2018
Scientist:
Transcript:

Heres a program from our archives.It's well known that bats and dolphins use pulses of sound to echolocate. Now there's evidence that yet another animal may have a built in sonar system - the hippopotamus. I'm Jim Metzner and this is the Pulse of the Planet.Ambience, Hippos Barklow: We found recently, through studies of blood proteins, molecular taxonomy, that hippos are the most closely related terrestrial organism to the whales and dolphins that is alive today.William Barklow is an associate professor in the department of biology at Framingham State College. On a recent trip to East Africa, he recorded a number of hippo vocalizations, and he found that the sounds are being transmitted both in the air and under water.Barklow: The common sound made by hippos, when you visit Africa, are referred to as a bellow. Also you hear in the background a lot of splashing and breathing. They expel air from their nose after a dive the same way that dolphins and whales do before taking the next breath.When Professor Barklow took the recordings of hippos bellowing and grunting, and slowed them down, he made an interesting discovery.Barklow: Those grunts are actually made up of individual, separate clicks that are repeated very quickly, like 30 times a second. Our ears are not good at resolving quick signals like that, so we hear it as a grunt. But in fact, every little sound of that grunt is an individual click. Those clicks are exciting because of the hippos supposed relation to the whales and dolphins. Dolphins, we know, echolocate using clicks. It is very possible that hippos also use click-trains underwater for echolocating. That's something that we have to look into.Here's a hippo's grunt at normal speed... and now here's the same sound slowed down, so that you can hear the clicks. This archival program is part of our thirtieth anniversary celebration. If you want hear more, check out our podcast.