Bats use rolled up leaves as trumpets!

By Casey Frye, CCNN Writer

lobster-claw
A lobster-claw plant.

Bats are known for their ability to use echolocation – sending out sound and listening for its echo to locate objects. Not only do the flying creatures use this to hunt for food, it’s also how they identify members of their own group. According to new research from University of Costa Rica biologists, the Spix’s disk-winged bat species uses rolled up leaves to increase the power of their sounds – just like a trumpet!

Usually, the creatures hide from predators and harsh weather inside the leaves of plants called lobster-claws and calatheas. However, the researchers realized that bats who huddled together inside never really recognized the calls of their buddies flying on the outside.

“We started to wonder if the leaf was somehow affecting call [accuracy],” said Gloriana Chaverri, a biologist at the university. Was it the narrow part of the leaf that was distorting the sound, or the wider opening? And, was the plant messing up both incoming and outgoing calls?

She and fellow biologist Erin Gillam created a simple experiment to see what the deal was. They blasted pre-recorded bat noises through a speaker at the narrow end of the leaf, towards a microphone at the wide end. They then switched the speaker and the microphone, sending the sound from the bigger opening towards the smaller one. By comparing the sound differences, they came across a unique discovery. Apparently, the bat calls going into the leaf were made louder because of the narrowing walls, yet outgoing calls were messed up and even quiet in some cases.

How is it that the bats could locate each other then? The researchers think that the calls contain just enough useful information to serve as a homing device, kind of like a trumpet. To unravel this mystery, the biologists will continue studying the bats.

Featured image courtesy of Alan Wolf on Flickr. Image of lobster-claw courtesy of Coley Cheng on Flickr.