Nav: Home

What role does mouth shape play for echolocating bats?

November 28, 2016

Washington, D. C. November 28, 2016 -- Echolocating bats are able to manipulate the acoustic projection pattern of their sonar pulse emissions -- but how they do it remains a largely unexplored mystery.

The Mexican free-tailed bat, Tadarida brasiliensis, appears to do it by adjusting the shape of its mouth cavity, aka beam forming, similar to the way humans purse their lips to create an "O" sound. While this is usual for humans, it is unusual for animals. Flying Tadarida lift their nose and lips before each echolocation pulse with a set of specialized facial muscles.

In a moment of serendipity while working on another project, Samantha Trent, a doctoral candidate working with Michael Smotherman at the Texas A&M Institute for Neuroscience, noticed a large group of muscles running straight down the middle of the top of the bat's skull. A set of muscles like this is quite unusual in size and location for a small mammal, so she questioned their purpose.

During the 172nd Meeting of the Acoustical Society of America and the 5th Joint Meeting with Acoustical Society of Japan, being held Nov. 28-Dec. 2, 2016, in Honolulu, Hawaii, Smotherman will present his work with Trent exploring the muscle's complex activity patterns during sonar performance, whether the muscle tissue displays necessary fast-twitch specializations to accommodate echolocation, and how manipulations of mouth shape altered 3-D beam patterns.

"It seems evident that this particular set of muscles is involved in changing the shape of the bat's mouth -- especially during echolocation," Trent said. "We think this aids the bat's ability to change the shape of its outgoing echolocation pulse beam."

To put this to the test, they used a microphone array to capture recordings from all around the bat's head to build a picture of the beam shape of sound coming out its mouth. They also recorded electrical activity from these muscles while the bats were freely echolocating to determine how these muscles are involved in producing echolocation pulse streams.

More specifically, electromyography (EMG) recordings from awake echolocating bats confirmed that the muscles in question were activated in precise temporal coordination with pulse emissions. The researchers also found that raising the bats' nose tip alone creates a small aperture and wide-angle beam, while simultaneously raising the front and side lips creates a wider aperture with a narrower beam. These results indicate that Tadarida possess a specialized neuromuscular tool for sonar beam forming.

"This type of vocal control is unique within the animal kingdom," Trent said. "It's exciting to study animals that have such special abilities and to show the public that bats really are cool, as our lab has always known them to be."

This project has several intriguing sonar applications. "[I'm] especially excited to bring engineers on board to collaborate and explore how this behavioral ability may be useful for building or improving sonar devices," Trent said.

Trent is doing her dissertation on this work, delving deeper into the neural mechanism underlying the bats' flexible vocal ability.

"We're eager to see where and how this behavior may be controlled within the brain," she noted.
-end-
Presentation 1aAB3, "Specialized facial muscles support sonar beam-forming by free-tailed bats," by Michael Smotherman is at 11:15 a.m. HAST, November 28, 2016 in Room South Pacific 4.

MORE MEETING INFORMATION

The 172nd Meeting of the Acoustical Society of America

The meeting is being held November 28-December 2, 2016 in Honolulu, Hawaii.

USEFUL LINKS

Main meeting website: http://acousticalsociety.org/content/5th-joint-meeting-acoustical-society-america-and-acoustical-society-japan

Technical program: http://acousticalsociety.org/asa2016fall.abstractcentral.com/planner.jsp

Meeting/Hotel site: http://acousticalsociety.org/content/5th-joint-meeting-acoustical-society-america-and-acoustical-society-japan#hotel

Press Room: http://acoustics.org/world-wide-press-room/

WORLD WIDE PRESS ROOM

In the coming weeks, ASA's World Wide Press Room will be updated with additional tips on dozens of newsworthy stories and with lay-language papers, which are 300-1200 word summaries of presentations written by scientists for a general audience and accompanied by photos, audio, and video. You can visit the site during the meeting at: http://acoustics.org/world-wide-press-room/

PRESS REGISTRATION

We will grant free registration to credentialed journalists and professional freelance journalists. If you are a reporter and would like to attend, contact Emilie Lorditch (elorditc@aip.org, 301-209-3029) who can also help with setting up interviews and obtaining images, sound clips, or background information.

LIVE MEDIA WEBCAST

A press briefing featuring a selection of newsworthy research will be webcast live from the conference on Wednesday, November 30th. Topics and times to be announced.

ABOUT THE ACOUSTICAL SOCIETY OF AMERICA

The Acoustical Society of America (ASA) is the premier international scientific society in acoustics devoted to the science and technology of sound. Its 7,000 members worldwide represent a broad spectrum of the study of acoustics. ASA publications include The Journal of the Acoustical Society of America (the world's leading journal on acoustics), Acoustics Today magazine, books, and standards on acoustics. The society also holds two major scientific meetings each year. For more information about ASA, visit our website at http://www.acousticalsociety.org

Acoustical Society of America

Related Bats Articles:

Why doesn't Ebola cause disease in bats, as it does in people?
A new study by researchers from The University of Texas Medical Branch at Galveston uncovered new information on why the Ebola virus can live within bats without causing them harm, while the same virus wreaks deadly havoc to people.
The genetic basis of bats' superpowers revealed
First six reference-quality bat genomes released and analysed
Bats offer clues to treating COVID-19
Bats carry many viruses, including COVID-19, without becoming ill. Biologists at the University of Rochester are studying the immune system of bats to find potential ways to ''mimic'' that system in humans.
A new social role for echolocation in bats that hunt together
To find prey in the dark, bats use echolocation. Some species, like Molossus molossus, may also search within hearing distance of their echolocating group members, sharing information about where food patches are located.
Coronaviruses and bats have been evolving together for millions of years
Scientists compared the different kinds of coronaviruses living in 36 bat species from the western Indian Ocean and nearby areas of Africa.
Bats depend on conspecifics when hunting above farmland
Common noctules -- one of the largest bat species native to Germany -- are searching for their fellows during their hunt for insects above farmland.
Tiny insects become 'visible' to bats when they swarm
Small insects that would normally be undetectable to bats using echolocation suddenly become detectable when they occur in large swarms.
Illumination drives bats out of caves
Researchers of the Leibniz Institute for Zoo and Wildlife Research and the Max Planck Institute for Ornithology have investigated how the illumination of bat caves affects the animals' behaviour and whether the colour of light makes a difference on their flight.
Bats may benefit from wildfire
Bats face many threats -- from habitat loss and climate change to emerging diseases, such as white-nose syndrome.
Ecology: Wildfire may benefit forest bats
Bats respond to wildfires in the Sierra Nevada Mountains in varied but often positive ways, a study in Scientific Reports suggests.
More Bats News and Bats Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.