Once
Smitten
By April Frawley
Bat studies enamor scientists, engineers
with promises of elusive secrets
The air inside the cave felt cool and damp, a welcome
contrast to the sizzling summer heat in East China’s
Shangdong Province.
Virginia Tech researcher Thomas Tucker positioned
his motion-capture scanners throughout the cave. Around
him, a mere 20 feet away, hundreds of bats clung to the
walls.
Tucker proceeded with his work, undeterred by the
possibility that bats might take flight and swarm around
his head.
His objective was to capture images of the bats and
triangulate their movements with scanners equipped
with technology called “lidar,” which uses light pulses to
generate 3-D images.
The idea was to show how the bats hugged the walls
and worked in concert as they exited the cave. It’s a process
that seems chaotic, but is actually intricately orchestrated
by the animals’ sophisticated sonar.
“I didn’t realize there were so many types of species
and that each bat perceives space differently,” said Tucker,
an associate professor of creative technology in the
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Motion-capture scanners are primed to triangulate the
movement of bats as they exit a cave in the Shangdong
Province in East China.
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Dane Webster, an associate professor in the College of
Architecture and Urban Studies, used his skills in 3-D
animation to model bats.
School of Visual Arts. “The one we were focusing on has a
complex radar system, and not all bats have it.”
Outside the cave, waiting for the swarm of bats to
emerge, was Nicole Abaid, who would use Tucker’s data as
part of her research.
An assistant professor in the Department of
Biomedical Engineering and Mechanics at Virginia Tech,
Abaid studies how systems involving multiple intelligent
agents coordinate to complete big tasks.
As it turns out, bats exemplify this collective behavior.
“Bats operate on the same sonar frequency, but
they have no problems, such as jamming,” Abaid said.
“Understanding how they do that can help engineers
design better systems that use active sensing, such as a
swarm of underwater vehicles.”
Bats — unlike fish, which Abaid has also studied
— don’t have any biological mechanism that links them
together. Instead, they rely on echolocation — nature’s
version of sonar — to sense each other and operate
collectively as they stream out of their cave.
How they manage this feat has long been a scientific
puzzle. The answers could help engineers trying to
develop new technologies.
“People have been looking at bat sonar for 60 years,
and we cannot reproduce it,” said Rolf Mueller, an
associate professor in the Department of Mechanical
Engineering of the College of Engineering, who blazed the
trail that led Abaid and Tucker to study bats in Chinese
caves. “How can they use sonar and do all the things they
can do that we cannot?”
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More than meets the eye
Bats owe some of their supersensory capabilities to
specially shaped facial structures.
Depending on the species, bats emit ultrasonic waves
either through their mouths or their noses. In some bats,
exquisitely detailed skin outgrowths called noseleaves seem
to serve as miniature megaphones to shape the waves.
Bats receive signals through their ears, and certain
species can reshape their ears to enhance their biosonar.
And they can adjust at lightning speed.
Human beings need three-tenths of a second to blink
an eye. In a single tenth of a second, a bat can change the
shape and reposition its ear, adjusting its ultrasonic hearing
pattern.
Bats’ uncanny abilities — and other engineering
marvels of the natural world — inform research at the
Center for Bioinspired Science and Technology, which
Mueller directs. The center is partially supported by the
Institute for Critical Technology and Applied Science
(ICTAS) at Virginia Tech.
Mueller splits his time between his lab at ICTAS II
in the life science corridor on Virginia Tech’s Blacksburg
campus and his lab at Shangdong University in China,
home to one of the largest collections of bat specimens in
the world.
“A good thing about China is it is blessed with bats,”
Mueller said. “The bats there are diverse and plentiful
despite pollution.” Particularly important for Mueller, two
groups of bats in China have especially sensitive sonar
systems.
And despite all the developments in air travel since
Fascinated with bats since he was a master’s student
then,
one thing hasn’t changed: airplanes still have fixed
at the University of Tuebingen, Mueller spends about four
wings.
months a year in China, where he and his team keep 20
“That imposes some limitations in take-off, landing,
bats in a colony.
and
maneuverability
at low speed,” said Javid Bayandor,
He hosts graduate students and visiting professors
an
associate
professor
in the Department of Mechanical
from various disciplines annually to study the creatures.
Engineering.
Along the way, Mueller has lured many a curious
“For 100 years, we’ve viewed flight in one particular
investigator into caves inhabited by the leathery,
way,”
Bayandor said. “The only way we can generate
screeching creatures of gothic fiction.
enough
lift to take off is by applying thrust generated by a
“To understand bats, we need people to help who
propulsion system.”
have different backgrounds,” Mueller said. “Bats have
And increased propulsion means increased fuel
many properties that push the boundaries of what animals
consumption.
can do, so I have found it not to be a difficult sell.”
Smaller vehicles inspired by bats’ flapping flight could
Tucker, who is associated with the Institute of
be much more energyCreativity, Arts, and
efficient. Bayandor imagines
Technology (ICAT), usually
that this could dramatically
scanned sites and landmarks
change local air travel and
for historic preservation. But
even personal commuting:
he was also adept at motionhe tells his students that
capture technology, a tool
they might one day send
he had used to study and
their kids off to elementary
assess early signs of injuries
school with winged
or valued traits in working
backpacks.
dogs.
But the principles of bat
Mueller thought the
flight
are elusive.
motion-capture technique
During flapping, bats
would be useful for studying
From the inside out: A view from the bat cave.
continuously distort the
bats, and so he lured
shape and size of their wings, which makes understanding
Tucker into the fold. The 30 days he worked studying
their flight challenging.
bats in China flew by, and he hopes to return. Like other
“The bat is singular because it has very minute
researchers at Virginia Tech, the fascination with the
control over its motion,” said Danesh Tafti, the William
flying mammals had gotten into his blood.
S. Cross Professor and interim department head of the
“That is my agenda,” Mueller said.
Department of Mechanical Engineering. “Bats have
control of all their fingers and the webbing in between,
Shaping the signal
and because of this, it’s difficult to replicate their wing
Leonardo da Vinci respected the bat.
motion. It is a very challenging problem to simulate on a
In his notes, the famous Renaissance artist-scientist
computer.”
sketched a flying machine with a wingspan that exceeded
Tafti’s goal is to break the wing motion down into
30 feet. The invention was unmistakably inspired by bats:
simple parts to help engineers develop a true, bat-inspired
The wings had pointed tips and were designed to twist
robotic wing.
as they flapped, powered by a pilot lying face down with
“That is my long-term vision,” he said. “If the team
hand cranks and foot pedals.
comes together, we could do some really good stuff, from
It would be 400 years before aviation pioneers Orville
measurements to making a bat-like robot.”
and Wilbur Wright demonstrated the first practical
Once developed, the tiny devices could be used for a
airplane on Dec. 17, 1903.
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variety of purposes, including locating people or searching
small, difficult-to-reach spaces.
Bayandor’s team at the Crashworthiness for Aerospace
Structures and Hybrids (CRASH) Lab has already built
award-winning robotic birds modeled after seagulls. They
are currently at work on the robotic bat, dealing with
topics ranging from understanding the complete flight
kinematics in bats, to their unsteady aerodynamics.
They aim to create a fully representative, bioinspired
flying system and collaborate with Mueller as well as
mechanical engineering professors Francine Battaglia and
Andrew Kurdila.
Bayandor agrees with Mueller that there’s just
something beguiling about bat research: “It manages to
entice a lot of students,” he said.
Decoding the hive mind
Abaid, another Mueller colleague, is interested in bats
because she studies swarms and other collective systems
in nature whose behavior could be useful in engineered
systems.
Imagine a swarm of underwater vehicles gliding across
the ocean floor, able to spread out, coordinate, locate, and
move among each other in the dark depths without the
Bats change the shape of their wings with the grace of a
champion pianist — but much more quickly.
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need for a leader making every decision. A multiple-agent,
wireless system of this type could cover more ground than
a submarine could, at a fraction of the cost. It could be
invaluable for collecting climate data, for example.
Bat-inspired communication could also enhance air
traffic control systems, said Abaid, who is working with
doctoral student Yuan Lin. “When bats wake up in the
evening, how do they schedule who goes through cave?”
she mused.
But first researchers have to truly understand
how bats echolocate and work collectively using sonar.
Scientists know about a couple of important strategies.
Bats avoid frequencies that scramble their sonar senses,
something that is a challenge for man-made devices.
“They also seem to be able to eavesdrop on each
other,” said Abaid, who was named one of Popular
Science magazine’s Brilliant Ten in 2014. “They may get
information from the echoes of their peers. If we can
figure out how to do this, we can develop systems that
benefit.”
And it’s not just engineered systems that could benefit
from some batty upgrades. Bats have strong social ties,
dynamics that could also help humans work better as
teams.
“With humans, we feel like we are above subconscious
interactions, but we are not,” Abaid said. “If we share
music, we will find we are walking in step to it.”
The art of bats
Dane Webster had always found himself at the
intersection of art and science, using his skills in 3-D
animation to create models and visualizations for short
films and games.
His interests led him to the Institute for Creativity,
Arts, and Technology, where researchers from diverse
disciplines come up with innovative ways to tackle
problems and conduct research.
An associate professor in the College of Architecture
and Urban Studies and director of the master of fine arts
in creative technologies program, Webster had deployed
his animation expertise for colleagues in the gaming and
film worlds.
Mueller, meanwhile, needed help with a project to
scan and animate the anatomy of bat specimens. Technical
problems with computerized tomography, or CT scans,
were making it difficult for him to create anatomical
models up to his standards, so he turned to Webster
through ICAT.
This time, instead of building monsters for movies,
Webster built a bat.
That effort led to a second project with Anupam
Gupta, a graduate student in the Department of
Mechanical Engineering, who wanted to analyze how
sonar beams change when bats alter the shape of their
noses.
Virginia Tech bat researchers take flight on location in China.
Their animation of the dynamic behavior of bat
noseleaves for the 166th meeting of the Acoustical Society
of America in San Francisco in December 2013 was
awarded first prize in the “gallery of acoustics” competition.
For the art students, “bat projects” are an entryway to the
world of funded research.
With help from Webster’s models, Mueller and his
students have built
a prototype of a batinspired sonar system,
which was presented
at the May meeting of
the Acoustical Society
of America.
“It is not the
norm in the arts to
work on real-world
applications,” Webster
said. “The students
take it seriously and
they work very hard
Rolf Mueller
on it.”
Like Tucker, Webster quickly succumbed to bat
fever. He and his team created animations of vampire
bat specimens for a Smithsonian exhibit in the National
Museum of Natural History. While working on a clip that
appears to show a bat skeleton coming to life, Webster was
fascinated to learn that vampire bats run on their wrists
and one-quarter of all mammals are bats.
“If I had more hours in the day, I would spend more
time reading about bats,” Webster said.
The bat cave as viewed through the lenses of Thomas Tucker, an
associate professor of visual arts.
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The little brown bat, once among the most numerous
mammal species in New England, has been severely
impacted by white-nose syndrome.
Researchers stand between
bats, growing peril
By April Frawley
Researchers have been trying to learn the secrets
of bats for decades, but one unmet need until the latter
quarter of the 20th century was the conservation and
management of bat populations in the wild.
Prior to the federal Endangered Species Act in 1973,
wildlife managers typically had been focused on gamekeeping, preventing overpopulation of animals such as
deer, turkey, and elk, and the prevention of over-hunting.
Less noticed were bats. But now, despite having
tremendous resilience, some species are on the brink of
extinction.
Enter wildlife biologist W. Mark Ford, an associate
professor with the College of Natural Resources and
Environment.
“Bats are amazing creatures,” Ford said. “They have
adaptions to deal with complex environments. They have
evolved these specialized traits that allow them to persist
in places that would be otherwise inhospitable, like caves
or mines.”
Ford realized there was a huge need for research on
bat populations while he was completing his graduate
studies and spending his first postgraduate year at the
University of Georgia.
As the unit leader of the Virginia Cooperative Fish
and Wildlife Research Unit, Ford and his team conduct
research and supply data to help federal and state wildlife
managers make important decisions. For example, if an
agency wants to do cut down trees, they need to know
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what effects that decision could have on the animals there.
Bats are a part of this equation, Ford said.
He has been studying the effects of a fungus that
attacks bats when they hibernate — a disease called
white-nose syndrome. It has spread from central New
York to at least 25 states and five Canadian provinces since
2006, killing more than 6 million bats.
Because bats affected by this condition are now so
rare, researchers have had to develop better ways to track
them.
One of the methods Ford and his colleagues use
involves tracking bats by their sounds. Using sound
detectors, the researchers can analyze the noises they
capture and determine what types of bats made them.
Knowing which bats are in a given area is crucial for
land managers, who otherwise might do controlled burns
or cut down trees where near-extinct bats live.
Listening to bats is noninvasive, avoiding
unintentional transfer of the spores of the fungus that
causes white-nose syndrome that could occur with
handling the creatures.
“Bats are very intelligent and are important
components of the ecosystem,” said Ford, whose team
has projects across the eastern United States. “Mexican
tree-tailed bats in Texas consume billions and billions of
insects that would prey on cotton and corn. They save
us lots of money on insecticides, and we really need to
understand them.”
The poetry of Nikki Giovanni
made an indelible impression
on a biologist, who thought he
ought to say thanks.
A poet’s words in flight
Not everyone has a bat named in their honor
Throughout her career, world-renowned poet, activist,
and University Distinguished Professor of English Nikki
Giovanni has received countless honors and awards — not
the least of which was having a species of bat named in
her honor.
Robert Baker, a Horn professor of biological sciences
at Texas Tech University, discovered the new species in
2001 during a research excursion in West Ecuador. The
discovery, said Baker, allowed him a unique opportunity in
the scientific world.
“There are literally millions of stars in the sky to
be named, but probably no more than 2,000 species of
mammals remain to be named,” Baker said. “In the grand
scheme of things, using one of those opportunities to
make a statement about somebody is a special deal.
“I decided to choose someone whose life work I
respected immensely, but that I had never had contact
with. It was a way of going outside of my own world.”
Baker selected Giovanni in 2004 and dubbed the
species, “Micronycteris giovanniae,” meaning Giovanni’s
small night flyer.
“I enjoy reading her poetry and I come from the Deep
South, so I really can appreciate what she has done for
race relations and equality,” Baker said. “I’ve got some of
her writings hanging on my wall ... so this is somebody
you ought to say thanks to.”
Baker remembers breaking the news to Giovanni,
who is with Virginia Tech’s College of Liberal Arts and
Human Sciences.
“I wrote to her, ‘You don’t know me and this isn’t a
joke, but I want to name a bat after you.’” Baker said. “I
told her it was a serious honor, but I wished to have her
permission and not to offend her.”
Giovanni — thrilled by the proposition —
accepted and even touted her newly acquired honor to a
Washington Post reporter, Baker said.
“They did a story on her after she was nominated for
a couple of humanitarian awards,” Baker said. “She said
she didn’t care, because she was special — she had a bat
named after her.”
Adapted from a Texas Tech University news release.
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