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(Bio) (Phys) Bats and Sonar: Echoes of Hunting

 
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PostPosted: Fri Apr 28, 2006 6:30 am    Post subject: (Bio) (Phys) Bats and Sonar: Echoes of Hunting Reply with quote






Echoes of Hunting
26 April 2006
Sarah Webb
http://www.sciencenewsforkids......ature1.asp

If you go by what you see in cartoons or vampire movies, you might think that bats are big, scary, blood-sucking creatures that come out only at night.

Certainly, many bats are active at night and asleep during the day. They have sharp teeth. A few species do feed on blood. These vampire bats, which are actually quite small and rare, typically target birds, cattle, pigs, and other animals. When most bats are hungry, however, they stick to insects or fruit.

Because they usually hunt at night, bug-eating bats have developed a special system for finding insects in the dark. In much the same way as dolphins use sound to locate objects underwater, bats use information from sounds to "see" their prey in the dark. This process is called echolocation.

Scientists are studying bats and their use of echolocation to learn more about how bats process information to understand and adapt to the world around them.

High-pitched squeals

When bats use echolocation to hunt, they make high-pitched squeals that people can't hear but that other bats can detect. If there's a bug or another object nearby, the sound bounces off the object and comes back to the bat.

"They can tell where the bug is by listening to the difference in the sound at the left and right ears," says Cindy Moss, a psychologist at the University of Maryland in College Park.

And a bat can tell how far away an object is by keeping track of the time between when it makes the sound and when the echo returns, she says. If an object is nearby, the sound comes back quickly. If the object is farther away, the reflected sound takes longer to travel back to the bat's ear.

"They're performing calculations in their minds all the time in much the same way that we perform calculations about what it is that we see," says Ellen Covey. She studies bats at the University of Washington in Seattle.

Big brown bats

Moss is interested in big brown bats, which live in dark places such as attics and barns and under the eaves of buildings throughout most of the United States and Canada.

Using echolocation, a big brown bat can swoop down, capture a bug, and eat it—all in about 2 seconds.

Scientists studying big brown bats in the wild have observed that they change both the pitch and the timing of their calls depending on whether they're looking for food or whether they've already found a bug that looks like a tasty dinner.

When they're searching for food, bats tend to use longer sound pulses to locate bugs flying in the open. When they notice a bug, they begin to make fast, high-pitched noises that, in general, get faster and higher as they close in for the kill.

Using sound like a flashlight

Clearly, bats know how to zero in on their food. They not only make appropriate sounds but also appear to have no trouble analyzing the echoes that come back to their ears.

To learn more about how bats process the information that they gather, Moss and her coworkers set up lab experiments to see how bats use echolocation while doing simple tasks.

The researchers tied a bug to a string and hung it from the ceiling of a dark room. Then, they used high-speed infrared cameras and special audio equipment to record a bat's calls as it hunted for the bug.

Moss and her students found a close connection between where a bat "looks" and how it flies. A bat directs its sound beam, like a flashlight, ahead of its flight. As the bat moves its head in the direction in which it calls, its body turns in the same direction

Bats convert what they see into what they do in much the same way that people convert what they see into action. For example, if you're hungry and see an ice cream truck to your left, your head turns to the left. Your body then turns to the left as you begin walking to the truck.

The researchers also discovered that when a bat makes calls at a fast rate as it turns, it turns more quickly than it does when calling at a slower rate.

Obstacle course

Finding a bug that's hanging from a string in the middle of an empty room is easy for a bat. That's because bats normally hunt in environments in which insects flit among other objects, such as trees, buildings, or animals.

To make things harder for the bats in the lab, Moss and her coworkers tied bugs to a string and hung them in front of a plant. Now, the bats would have to sort out echoes that came not only from the bug but also from the plant.

A plant's echoes can serve as camouflage for a bat's prey. In that case, a bat has a more difficult task and has to use different strategies to find the prey, Moss says. The researchers found that, when the hanging bug was 20 centimeters from a plant, a bat located the bug about 80 percent of the time. When the bug was 10 centimeters from the plant, the bat needed more time and caught a meal about half as often.

When the bug was hanging 40 centimeters away, the bat hunted almost as efficiently as if the plant weren't in the room.

So, even with extra, misleading echoes, bats can find food. But, it turns out, they adjust the timing of their signals to help make up for the clutter.

Decoding sounds

Many bat researchers have studied both the length and pitch of individual sounds that bats make as they hunt. In their studies, Moss and her coworkers observed something new. Bats can adjust their sound output to respond to information they receive by echolocation. What's more, they produce pulses in distinctive patterns.

When bats hunt for a bug against a background object, they repeat particular patterns of sound, Moss says. She calls these patterns strobe groups. They resemble the repeated flashes of a strobe light.

"We started seeing sound groups again and again and again," Moss says. "And we did some recording in the field, and there they were."

Such groups of sounds may allow a bat to sharpen its view of a space and help it recognize the difference between an insect and shrubs or grass in the background.

The work that Moss and her students have done in identifying these patterns is a useful step in understanding how a bat processes information, Covey says.

"It's important to look at the context of the sounds and not just the individual sounds," she adds. Sounds mean different things depending on what went before and what comes after.

So, in the seconds that it takes a bat to swoop down and capture a meal, it's using a complicated sonar system that scientists are only beginning to understand. There might even be similarities between the way that bats process their echolocation patterns and the way that people process sound patterns to understand speech.

That's something to ponder the next time you're out at night during the spring or summer and happen to glimpse a bat on the hunt.

*************************************************************

Questions to explore further this topic:

What are chiroptera?

http://www.ucmp.berkeley.edu/m.....ptera.html
http://tolweb.org/Chiroptera

What are bats?

http://members.aol.com/bats4kids/
http://www.cccoe.k12.ca.us/bats/
http://www.bats.org.uk/kids/kids_discoverbats.asp
http://www.npca.org/wildlife_p.....acts/bats/
http://dep.state.ct.us/burnatr.....s/bats.htm
http://www.enchantedlearning.c.....mmals/bat/

How are bats classified?

http://www.ucmp.berkeley.edu/m.....irosy.html

What are the different species of bats

http://animaldiversity.ummz.um.....ninae.html
http://www.batconservation.org.....urbats.htm
http://www.batconservation.org.....icles.html
http://www.bio.bris.ac.uk/rese.....itishbats/

Bats in the Philippines

http://www.fieldmuseum.org/phi.....OPTERA.htm
http://www.txtmania.com/articles/bats.php
http://www.animalinfo.org/species/bat/nyctrabo.htm
http://mampam.50megs.com/wv/wv96report.html

A slideshow about bats

http://www.batconservation.org.....eshow.html

Photographs of Bats

http://www.batconservation.org.....raphs.html

Stellaluna: A Lesson on Bats for Children

http://projects.edtech.sandi.n.....quest.html

What are vampire bats?

http://www.nationalgeographic......ebats.html
http://www.thewildones.org/Animals/vampire.html
http://www.batconservation.org.....ampire.htm
http://bss.sfsu.edu/geog/bholz.....ampire.htm

What is a big brown bat?

http://ohiodnr.com/wildlife/Re.....pub372.htm
http://animaldiversity.ummz.um.....uscus.html

Do bats have special skills?

http://www.newsdesk.umd.edu/sc.....cleID=1231

Animations on how a bat captures an insect

http://www.bsos.umd.edu/psyc/batlab/movies.html

Movies on how a bat captures an insect

http://www.newsdesk.umd.edu/sc.....cleID=1214
http://www.newsdesk.umd.edu/sc.....icleID=965

Movies about bats

http://www.batconservation.org.....rogram.mov
http://www.batconservation.org.....ser%7E.mov


Natural History of Bats

http://www.batcon.org/home/index.asp?idPage=121

Ecology of bats

http://www.ucmp.berkeley.edu/m.....irolh.html

Diversity and Distribution of Bats

http://www.batcon.org/home/ind.....SubPage=52

Are some bat species endangered?

http://www.fws.gov/endangered/bats/bats.htm
http://www.kidsplanet.org/factsheets/bat.html

Bats and Rabies

http://www.batconservation.org.....abies.html
http://www.cdc.gov/ncidod/dvrd.....s&.htm

*************************************************************

What is sound?

http://omp.gso.uri.edu/work1/science/whatis/1.htm

How is sound characterized?

http://omp.gso.uri.edu/work1/science/whatis/2.htm

Intensity or loudness
http://omp.gso.uri.edu/work1/s.....ensity.htm

Frequency of pitch
http://omp.gso.uri.edu/work1/s.....quency.htm

Wavelength
http://omp.gso.uri.edu/work1/s.....length.htm

How are sounds made?

http://omp.gso.uri.edu/work1/science/whatis/3.htm

How is sound measured?

http://omp.gso.uri.edu/work1/s.....urng/1.htm

How fast does sound travel?

http://omp.gso.uri.edu/work1/s.....oves/1.htm

What is seeing with sound?

http://www.biosonar.bris.ac.uk/contents.htm

What is echolocation?

http://members.aol.com/bats4kids/echo.htm
http://ace.acadiau.ca/math/kar.....ation.html

Echolocations of bats

http://www.eparks.org/wildlife.....cation.asp
http://www.museumca.org/caves/onli_echo.html
http://library.thinkquest.org/5813/echo.htm
http://www.tigerhomes.org/anim.....vision.cfm

A Lesson on echolocation

http://www.fi.edu/wright/again.....howto.html
http://www.accessexcellence.or....._echo.html

Echolocations and blind humans

http://hcs.harvard.edu/~husn/BRAIN/vol1/echo.html

How does an insect defend against echolocation?

http://members.aol.com/obcbats/ecolocation.html
http://en.wikipedia.org/wiki/Animal_echolocation

What other animals use echolocation?

http://www.dolphinkind.com/echolocation.html
http://www.cbmwc.org/education/echo.asp
http://www.pbs.org/odyssey/ody.....cript.html
http://oceanlink.island.net/oi.....ocate.html
http://teacher.scholastic.com/dolphin/about5.htm
http://library.thinkquest.org/.....ation.html

Science of Sound in the Seas

http://omp.gso.uri.edu/work1/science/ssea/1.htm

How does sound in air differ from sound in water?

http://omp.gso.uri.edu/work1/science/ssea/3.htm

What is sonar?

http://omp.gso.uri.edu/work1/science/ssea/1a.htm
http://oceanexplorer.noaa.gov/.....sonar.html
http://en.wikipedia.org/wiki/Sonar
http://terraweb.wr.usgs.gov/TR.....ereySonar/
http://solmar.saclantc.nato.in.....sonar.html

The Sonar system of dolphins

http://instruct1.cit.cornell.e.....avior.html

Protecting whales and dolphins from human sonar

http://www.nrdc.org/wildlife/marine/sonar.asp

What are sonars used for?

http://www.pbs.org/wgbh/nova/lochness/sonar2.html
http://www.nprb.org/education/fish-0202.htm
http://education.usace.army.mi.....s5lv2.html

What is side-scan sonar?

http://www.abc.se/~pa/mar/sidescan.htm
http://oceanexplorer.noaa.gov/.....ndping.pdf

GAMES

http://www.batcon.org/educatorsk/kidzcave.asp
http://www.batconservation.org.....tQuiz.html
http://www.sciencenewsforkids......ksheet.asp
http://www.sciencenewsforkids......rdfind.asp


Last edited by adedios on Sat Jan 27, 2007 3:51 pm; edited 2 times in total
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PostPosted: Fri Apr 28, 2006 12:31 pm    Post subject: Sonar May Be Linked to Stranding of Whales Reply with quote

Sonar May Be Linked to Stranding of Whales
By The Associated Press

posted: 28 April 2006
01:20 pm ET


HONOLULU (AP)—The Navy's use of sonar during maritime exercises may have contributed to the mass stranding of more than 150 whales in Hawaii's Hanalei Bay two years ago, government scientists said.
The National Oceanic and Atmospheric Administration said the finding—along with information from other studies—has led it to ask the Navy to reduce its sonar's power during exercises planned this summer in Hawaiian waters. It also asked the Navy to turn off its active sonar when the whales come within a set distance.

The Navy says it will comply with the agency's requests, but said the report released Thursday did not conclusively show sonar triggered the stranding.

Officials were unable to find other reasons that may have caused the melon-headed whales to swim into the bay on July 3, 2004. One whale beached itself and died a few days later, said Brandon Southall, director of NOAA's acoustics program.

Nearby predators or other factors may have also contributed to the incident, NOAA said in the report.

The Navy uses sonar technology to detect threats and to navigate. Some wildlife advocates believe the sound waves hurt whales, possibly by damaging their hearing or causing them to rise to the surface too quickly and get decompression sickness.

The day before the whales entered Hanalei Bay, six U.S. and Japanese vessels steamed north from the island of Oahu toward Kauai, intermittently using active sonar signals.

NOAA's study concluded the whales—which usually inhabit only deep water—may have heard thee signals and headed into the shallow water.

Lt. William Marks, Navy spokesman at the Pentagon, said the six-hour gap between the last use of sonar and the whales' arrival made it unlikely sonar triggered the stranding.

But environmentalists said the report clearly blamed sonar.

"It adds to a long and growing use of strandings that have been associated with the Navy's use of sonar,'' said Michael Jasny, senior consultant with the Natural Resources Defense Council in Los Angeles, citing other mass strandings in the Canary Islands, Alaska and Japan.
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PostPosted: Thu Aug 10, 2006 9:04 am    Post subject: Baby Bats Babble Like Human Infants Reply with quote

Baby Bats Babble Like Human Infants

By Ker Than
LiveScience Staff Writer
posted: 09 August 2006
12:22 am ET



Baby bats babble just like newborn human babes, a new study finds.

Babbling is thought to be a kind of vocal play that provides human infants a chance to train their vocal tract muscles in preparation for speech and to practice combining the syllables they will use as adults. Humans begin babbling at about 7 months of age.

Apart from a few other primates, like the pygmy marmoset, babbling has never been observed in any other mammals until now. However, certain species of songbirds are known to engage in a similar behavior, called "subsong."

For the full article and audio:

http://www.livescience.com/ani....._bats.html
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PostPosted: Wed Nov 29, 2006 7:57 am    Post subject: Bat's Wrinkly Face Improves Sonar Reply with quote

Bat's Wrinkly Face Improves Sonar

By Charles Q. Choi
Special to LiveScience
posted: 28 November 2006
08:38 am ET

The strangely intricate wrinkles and grooves around the nostrils of many bats apparently could help them "see" in the dark by focusing their sonar, scientists in China have found.

The discovery could help scientists improve sonar and radio technology, the researchers said.

Bats are famous for their ability to "see" in the dark by listening to the echoes of their ultrasonic calls. This is known as echolocation, or "biosonar."

While most bats emit sonar from their mouths, roughly 300 species fire it from their noses. These bats often have bizarrely elaborate, intricately shaped flaps dubbed "noseleaves" around their nostrils that are adorned with grooves and spikes.

For the full article:

http://www.livescience.com/ani.....faces.html
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PostPosted: Wed Dec 06, 2006 7:28 pm    Post subject: Batty Discovery: The Longest Tongue Reply with quote

Batty Discovery: The Longest Tongue

By Jeanna Bryner
LiveScience Staff Writer
posted: 06 December 2006
01:02 pm ET

One nectar bat can launch its tongue three and a half times its body length, longer than any other mammal and second only to chameleons among vertebrates, scientists recently discovered.

The tube-lipped nectar bat (Anoura fistulata) was discovered in the cloud forests of the Andes of Ecuador, and first described last year.

But it wasn’t until recently that scientists realized the tongue of this bat extends twice as far as its family members. They suggest this long licker evolved to feed on a flower where the nectar is hidden at the end of equally long funnels. That gives the nectar bat sole pollinating rights to the flower.

For the full article:

http://www.livescience.com/ani.....ongue.html
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PostPosted: Wed Feb 14, 2007 7:36 am    Post subject: Bats Found to Feed On Migrating Birds at Night Reply with quote

Bats Found to Feed On Migrating Birds at Night

By Charles Q. Choi
Special to LiveScience
posted: 13 February 2007
08:00 pm ET

The blood of the largest bat in Europe reveals it can devour birds in midair at night, the only animal known to do so thus far, evidence now strongly suggests.

Roughly five billion songbirds migrate across the Mediterranean Sea every year, mainly at night. Although more than 90 percent of these birds weigh on average less than 20 grams (0.7 ounces), this could amount to about 100,000 metric tons of food upon which predators might wish to dine. (A metric ton is equivalent to 2,204 pounds).

No animal, however, was known to hunt the birds while they flew at night. Falcons catch migratory birds along the Mediterranean only during the day, while owls and some tropical bats capture vertebrate prey on or near the ground or other surfaces at night.

For the full article:

http://www.livescience.com/ani.....ators.html
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PostPosted: Mon Feb 19, 2007 9:41 am    Post subject: Freaky New Bats Found by DNA Barcoding Reply with quote

Freaky New Bats Found by DNA Barcoding

By Jeanna Bryner
LiveScience Staff Writer
posted: 18 February 2007
12:00 pm ET

Most species on Earth, including a number of bats, still fly under the radar of scientists, but a high-tech method that identifies animal species based on a snippet of DNA is starting to weed out concealed organisms.

Two studies detailed in the current issue of the journal Molecular Ecology Notes found the method, called DNA barcoding, can reveal entire assemblages of species, including new genetically distinct bird and bat species.

One of the newly discovered bat species feasts on frogs. All of them are freakish looking in that uniquely bat way.

For the full article:

http://www.livescience.com/ani.....rcode.html
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PostPosted: Tue Apr 10, 2007 9:05 am    Post subject: Study Reveals How Drunken Bats Sober Up Reply with quote

Study Reveals How Drunken Bats Sober Up

By Charles Q. Choi
Special to LiveScience
posted: 10 April 2007
08:17 am ET

Bats often risk getting drunk off cocktails of alcohol that stew inside ripened fruit. And just as driving is dangerous for intoxicated humans, so is flying for boozy bats.

Now scientists find bats are savvy enough to dine on certain types of fruit sugar to help them get over the ill effects of alcohol. These findings could shed light on how wildlife deals with alcohol.

Bats make up one-quarter of all mammal species. Almost one-third of all bats live on the juices of fruits and the nectar of flowers.

Fruits such as figs and dates accumulate ethanol, or drinking alcohol, as they ripen. While Egyptian fruit bats (Rousettus aegyptiacus) prefer such fruits when they are ripe, as little as a 1 percent concentration of ethanol is toxic for the bats. Even concentrations of less than 1 percent ethanol can make fruit bats sluggish against predators or hamper their ability to avoid obstacles. (For comparison, pale lager beers that most consumers are familiar with are typically 5 percent alcohol by volume.)

For the full article:

http://www.livescience.com/ani.....chies.html
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PostPosted: Fri Jun 15, 2007 1:07 pm    Post subject: Fruit Bats are not ‘Blind as a Bat’ Reply with quote

Fruit Bats are not ‘Blind as a Bat’
15 June 2007
Max Planck Society


German-American research team finds daylight photoreceptors in the retinas of nocturnal fruit bats

The retinas of most mammals contain two types of photoreceptor cells, the cones for daylight vision and colour vision, and the more sensitive rods for night vision. Nocturnal bats were traditionally believed to possess only rods. Now scientists at the Max Planck Institute for Brain Research in Frankfurt and at The Field Museum for Natural History in Chicago have discovered that nocturnal fruit bats (flying foxes) possess cones in addition to rods. Hence, fruit bats are also equipped for daylight vision. The researchers conclude that cone photoreceptors might be useful for spotting predators and for social interactions at periods of roosting during the day. Flying foxes often use exposed treetops as daytime roosts, where they assemble in large colonies (Brain, Behavior and Evolution, online May 2007).

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http://www.mpg.de/english/illu.....e20070612/
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PostPosted: Tue Jul 10, 2007 7:48 am    Post subject: Now Hear This: Sonar Doesn't Hurt Trout Reply with quote

Now Hear This: Sonar Doesn't Hurt Trout
By Tuan C. Nguyen, LiveScience Staff Writer

posted: 10 July 2007 08:14 am ET

The military's use of sonar poses no threat to fish, a new study suggests.

The finding, detailed in the July issue of the Journal of the Acoustical Society of America, showed that rainbow trout exposed to high-intensity, low-frequency sonar experienced only a small and presumably temporary decline in hearing sensitivity.

There has been considerable concern in recent years over the potentially damaging effects of man-made sounds on marine life. In the past, environmental advocacy groups have sued the U.S. Navy to halt underwater sonar use, claiming that the technology harms or even kills whales, dolphins and other forms of marine life.

The new study, funded by the Navy, was designed to explore the effects of Navy ship sonar on fish swimming nearby.

For the full article:

http://www.livescience.com/ani.....sonar.html
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PostPosted: Tue Sep 18, 2007 12:49 pm    Post subject: Why Whales Developed Sonar Reply with quote

Why Whales Developed Sonar
By Tuan C. Nguyen, LiveScience Staff Writer

posted: 18 September 2007 08:23 am ET

When whales first took the plunge into the ocean from land about 45 million years ago, they lacked the ability to echolocate—that is, to find and identify objects by emitting and bouncing sounds off them, much as bats do.

About 7 million years later, toothed whales (sperm whales are a type of toothed whale) developed this ability, fossils show.

For the full article:

http://www.livescience.com/ani.....hales.html
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PostPosted: Thu Oct 18, 2007 12:00 pm    Post subject: Researchers studying how singing bats communicate Reply with quote

Texas A&M University

Researchers studying how singing bats communicate

COLLEGE STATION, Oct. 18, 2007 – Bats are the most vocal mammals other than humans, and understanding how they communicate during their nocturnal outings could lead to better treatments for human speech disorders, say researchers at Texas A&M University.

Thousands of bats native to Central Texas fly overhead each night singing songs of complex syllables – but at frequencies too high for humans to hear.

Texas A&M researcher Michael Smotherman is trying to understand how Mexican Freetail bats organize syllables into songs and how their communication is linked to the brain. “If we can identify those areas in a bat brain [responsible for communication], we can learn more about how a normal [human] brain generates and orchestrates complex communication sequences,” Smotherman says. “And by understanding how that works, we can then come up with testable hypotheses about what might be going on in speech disorders.”

The researchers in Smotherman’s lab are studying two aspects of bat communication. In behavioral studies, they examine sex differences and seasonal variations in communication, and in physiology studies they try to locate the parts of the bat brain active during communication.

Mexican Freetail bats sing mostly in ultrasonic frequencies that are right above the upper limit of human hearing. Humans can sometimes hear little bits of bat songs, however, when parts of syllables drop low enough.

Bats communicate at such high frequencies because of their ability to echolocate, which means they project sound and use the echoes to determine the direction and distance of objects. As the frequency of the bat’s sound gets higher, it can detect a more detailed picture of its surroundings.

Smotherman says Mexican Freetail bats use between 15 and 20 syllables to create calls. Every male bat has its own unique courtship song. The pattern of all courtship songs is similar, but each male bat uses a different syllable in its distinctive song. Bats also use sophisticated vocal communication to draw territorial borders, define social status, repel intruders, instruct offspring and recognize each other.

“No other mammals besides humans are able to use such complex vocal sequences to communicate,” Smotherman says.

The songs bats sing are similar to bird songs. Scientists have understood the link between bird songs and the bird brain for years, but “the architecture of a bird brain is very different from that of a mammal brain,” Smotherman explains, “so it is difficult to apply knowledge about bird communication to human speech.”

The brains of all mammals are organized in basically the same way, so a bat brain has many of the same structures as a human brain. This makes it easier to infer things about human speech from studying bat communication. The researchers’ first goal is to locate the part of the bat brain responsible for singing. “The bat brain has to have some higher vocal center that’s responsible for organizing these [vocal] sequences and patterns, and we just don’t know where it is yet,” Smotherman says. “So we’re using molecular techniques to identify which regions of the brain are most active during singing.”

Smotherman and his team maintain about 75 bats in their lab. They usually collect the bats from schools and churches that report bats in their buildings. “[By doing this,] we don’t have to feel like we’re taking them out of the wild,” Smotherman says. He adds that the bats are not aggressive and are a “fantastic bat for the lab because they are quite friendly.”

Smotherman hopes that over the next decade, the group can apply its research to knowledge of human speech and help shed light on language disorders. “The fact that human speech is so unique has really constrained research in this area,” Smotherman says. “Compared to other areas of neuroscience, we’re way behind in understanding even the most basic issues of how [speech] works.”
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PostPosted: Wed Feb 27, 2008 11:06 am    Post subject: Flight without Sonar Reply with quote

Flight without Sonar
Emily Sohn

Feb. 27, 2008

Bats are famous for their ability to use sound to "see." The technique, called echolocation, involves making high-pitched sounds that bounce off objects and return to the animal. On the basis of the pattern of sound that comes back, a bat gets a good picture of what's out there.

More than one-fifth of mammal species alive today are bats. And most bats use echolocation to find prey and avoid bumping into things as they fly. But bats didn't always have such supersensory skills, say scientists who have found a fossil of one of the world's most ancient bats.

For the full article:

http://www.sciencenewsforkids....../Note2.asp
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