SEEING WITH EARS

Presented By:Ravikash Maurya

(14484sc038)Banaras Hindu University, Varanasi

This ppt was prepared for Seminar presentation purpose in M.Sc.

semester IVIn

Department of ZoologyInstitute of Science

Banaras Hindu University (BHU)Varanasi (India).

How to see with Ears??

This could be achieved by listening & interpreting of a sound coming from an object.

Ears are adopter of sound(signal) &

Brain is interpreter of signal.

This property is known as “Echolocation”.(Discovered by Griffin in 1938)

A new trending term is “Biosonar”.

An Echo is a reflection of sound after hitting an object.

What is Echolocation?

"Echolocation is a property of using echo to determine where objects are in space”

In other words, with the help of echoes, the brain draw an image of the objects.

Echolocation Is Used by AnimalsThere are some animals who have developed

property to Echo-locate objects without help of vision.

The property of echolocation is well developed in mammals.

Bats Dolphins Whales

Echolocating Animals

Echolocation is Only found in

Microchiropteran bats

Echolocation help them for

navigation & foraging in total

darkness.

Echolocation helps Whales to navigate

where vision is extremely

limited in range due to Absorption or

Turbidity.

Dolphin’s habitats have low visibility

due to dirty water & Turbidity.

Echolocation help them for foraging.

How do Animals echolocate??

The echolocating animals cry loud so that their sound become Echo after hitting the target.

Animals

Sound Echo

Target

Principle Of EcholocationEcho locating bats emit sound

Pulses(Clicks) of very high frequency and listen for returning echoes to form an auditory scene..

What a bat can detect by using echolocation

o Distance(Range)- by comparing the time of emitted pulse to the time of the returning Echo.

o Size- larger animals reflect more sound(high intensity) and smaller animal reflect less sound (low intensity).

o Movement- by comparing amount of echo obtained on Left & Right ear.

o Velocity- by taking advantage of Doppler Shift.Echo of higher frequency = Target is gaining.

Echo of lower frequency = Target is outstanding.

Phases & Sequence of Echolocation

Redrawn From: Simmons & Kick(1984)

There are 4 steps in Prey capturing by bats-1- Search2- Approach3-Track4-Capture

You should not forget that echoes of other bats in a space create a noise. Then, how a bat recognize it’s own voice in noise? The “JAR” solves this problem.

Noise of Other Bats

Bat

Experimental Evidence of JAR

What is JAR ?• Each bat change its

sound frequency to increase the difference between the two bat's sound frequencies.

• By doing this, they avoid jamming of echolocating calls.

Experimental Evidence• Gillam et al had provided

first experimental evidence of JAR.

• They presented “Playback stimuli” (recorded echolocating sounds of six different frequencies ) to bat.

Outcome

• The bat exhibit a JAR by increasing frequency of clicks from the given Playback stimuli.

Reference: Gillam E.H. et al. Rapid jamming avoidance in biosonar. Proc. R. Soc. B 274, 651–660 (2007)

Co-evolution of Bat & Prey

With the evolution of Echolocation in bat, their Prey has also been evolved.

Some important evolved escaping property of Prey are-

By interfering Bat’s Sonar System (eg. Tiger Moth).By flying in irregular pattern.By becoming just quiet. By having hairy wings.

22 MammalsGenome

Including 4 newly sequenced Bat genes

805,053 Amino Acids

Within2,326 Orthologous

Coding gene Sequences

Convergence of 200 loci

Strong Evidence for convergence in Bat & Bottleneck Dolphins

Convergent Evolution Of Echolocation

Reference: Parker et al. Genome-wide signatures of convergent evolution in echolocating mammals. Nature 502, 228-236(2013).

Learning From NatureMany equipment have been developed using the clue

of Natural Echolocation .

Examples of Some Echo-locating Inventions

All these equipment produce ultrasounds for echolocation .

RADAR

SONAR

Driverless Car

Tactic Devices for Blinds

Radar• RAdio Detection And Ranging• It is similar to bats, used for

Arial echolocation.• Radar uses Radio wave or

Microwave to determine the range, angle, or velocity of objects.

Sonar

• Sound Navigation And Ranging

• Similar to Dolphins, used for Underwater echolocation.

• It uses ultrasound to navigate.

Driverless Car• It uses Radar for navigation.

Downloaded from: Google official Blog (https://goo.gl/wYhSl2)

Tactic Devices for Blinds

Downloaded from: PhysOrg.com (http://goo.gl/Pura08)

Ben Underwood: The Superman Descriptions• Name: Ben Underwood• Life : 1992-2009 (17 Years Only)• Location: California (USA)• Handicapped : Yes. His eyes were

removed during operation of Retinoblastoma (a Retinal Cancer)

• Special Property: Ben used to echolocate the surrounding by producing “Click” Sounds (With His Tongue). He was able to locate buildings, playing football, riding bike etc.

• Death: When same cancer returned.• Tribute: His Mom wrote a book about

Him-“Echoes of an Angel”. Website: www.Benunderwood.comvD

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Blind men teach themselves to see with Ears

Downloaded from-http://goo.gl/hOkcmk

References1. Chiu C., Xian W., Moss C.F. Flying in silence: Echolocating bats cease vocalizing to avoid

sonar jamming. PNAS 105, 13116–13121(2008).2. Gillam E.H., Ulanovsky N., McCracken G.F. Rapid jamming avoidance in biosonar. Proc.

R. Soc. B 274, 651–660 (2007) .3. Jones G, Siemers B.M. The communicative potential of bat echolocation pulses.

Journal of Comparative Physiology A 197(5), 447-457(2011).4. Kno¨rnschild M., Jung K., Nagy M.,Metz M.,Kalko E. Bat echolocation calls facilitate

social communication. Proc. R. Soc. B 279, 4827–4835(2012) .5. Madsen P. T., Surlykke A. Functional Convergence in Bat and Toothed Whale Biosonars.

Physiology 28, 276–283(2013).6. Parker J., Tsagkogeorga G., Cotton J.A., Liu Y., Provero P., Stupka E., Rossiter S.J.

Genome-wide signatures of convergent evolution in echolocating mammals. Nature 502, 228-236(2013).

7. Shnitzler H.U., Kalko E.K.V. Echolocation by insect-eating bats. BioScience 51, 557-569(2001).

8. Surlykke A, Kalko E.K.V. Echolocating Bats Cry Out Loud to Detect Their Prey. PLoS ONE 3(4), 1-10(2008).

9. Whitelow W. L. Au, Simmon J. A. Echolocation in Dolphins and Bats, Physics Today, 40-45(2007).

Thanking You..