Biodiversity

Tuesday, May 16, 2006

DISCUSSION OF ECHOLOCATION IN BATS AND WHALES

The echolocation is the ability that bats and whales posses and enables them to locate and discriminate objects by listening for echoes. Bats and whales use echolocation for different purposes for instance hunting, navigating and to judge the distance of the object.

Bats have ability to hear the sound when it bounces off from the object. When an object hits an echo sound come back to the bats (5). They can able to estimate the distance, movement as well as well as size of the objects in their way. They can even tell the shape and texture of tiny insects from its echo. Some bats send echolocation sound through their nose but the majority of bats use their mouth. They hold their mouth open as they fly.

Different species of bats uses different pattern of echolocation frequencies to find food and navigate. There are some species that produce constant frequency (CF) cry and those that use modulated (FM) call descend in pitched. “High frequency echolocation calls produced by bats range from 20-200 kilohertz" (1). It is difficult for human to hear the high pitched sound of the bats.

In the basic principles of echolocation, bats produce sound the same way as humans do, by moving air past their vibrating vocal chord. Bats use this echolocation process to gather information in order to see the world around them. Scientists believe that the strange noise that found in some bats, serves to focus the noise for more accurate pin pointing of insects such as grasshopper, moths, beetle and other prey.

The brains of bats process the returning information the same way. The bats are able to detect if the insects is on the left or right by using the sound. If the sound reaches the right ear before it reaches the left ear it means that the insects are on the right. The bats have ears which have complex collection of folds of the outer ear that help it to determine the vertical position of an insect. Echoes coming from below will hit the folds of the outer ear at different point than sounds coming from above, and so will sound different when they reach the inner ear of the bats.

Whales used echolocation for navigation and hunting. “Toothed whales developed the capability of emitting sounds that travel from their melons or foreheads and reflect off objects” (2). Toothed whales echo locate by producing clicking sounds and then receiving and interpreting echo. Toothed whales use echolocation to sense objects. Whales sent out high pitched whales, the sound bounces off, the objects and some returns to the whales. The whale interprets the returning echo to determine the objects shape, direction and distance. Toothed whales produce sound to overlapping functions. That is communicating and echo locating.

Tones of lower frequencies that are produced by whales include groans and moans. These sounds make a lot of noise and travel a long distance. The echoes produced by these sound can be used by whales to navigate. Thereafter, echoes returned as allow the frequency sound to bounce off of features in the oceans basis such as islands, sea mounts and continental shelves, and this could easily give the whales information about its environment. The sound also gave the whales little information about the other in the closer surrounding area.

Echolocation plays an important role into the life of bats and whales. Both whales and bats are able to hunt food, navigate and to judge the distance in which the insects is located. They have capacity to emit sound that travel like waves and reflect object.

References

1. Bennu A.N. The night is alive with the sound of Echoes [Internet].Catching Dinner on the Fly...; 2006 May 24, 11:03 UTC [Cited 2006 May 24]. Available from: http://research.amnh.org/users/nyneve/bats.html

2. Drum L. Cetacea. Echolocation [Internet]. Mammals; 2006 May 24, 11:03 UTC [Cited 2006 May 24]. Available from: http://nmml.afsc.noaa.gov/education/cetaceans/cetaceaechol.htm3
3. Kruse M. Echolocation in the bat [Internet]. Model System in Neurothology; 2006 May 24, 11:03 UTC [Cited 2006 May 24]. Available from: http://www.npa.uiuc.edu/courses/physl490b/models/bat_echolocation/bat_echolocation.html

4. Harris T. Seeing with sound [Internet]. How bats work; 2006 May 24, 11:03 UTC [Cited 2006 May 24]. Available from: http://science.howstuffworks.com/bat2.htm

5. Phillips J.D.Whales [Internet]. Marine Research Program; 2006 May 24, 11:03 UTC [Cited 2006 May 24].Available from: http://whale.wheelock.edu/archives/ask98/0306.html

6. Roth J. Echolocation [Internet]. National Parks; 2006 May 24, 11:03 UTC [Cited 2006 May 24].Available from: http://www.eparks.org/wildlife_protection/wildlife_facts/bats/echolocation.asp

7. Wikipedia Contributors. Bats [Internet] Wikipedia, The Free
Encyclopedia; 2006 May 09, 13:07 UTC [cited 2006 May 09]. Available from: http://en.wikipedia.org/wiki/Bats

8. Wikipedia contributors. Whales [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 09; 12:09 UTC Available from: http://en.wikipedia.org/wiki/Whales

Masiya Kedibone
CSIR Pretoria
0001
Cell No: 073 2519071
Tel No: 012 8412123
Fax: 012 842 3676
E-mail:kmasiya@csir.co.za

1 Comments:

  • You never actually cite most of your references - this would've been useful, especially when imparting particular information about frequency modulation or whatever (there still seems to be some confusion about referencing, and some stuff that's borderline plagiarism). Also, you left my tracked changes in your concluding paragraph - not a smart move!

    Cheers
    Nick

    By Blogger NcK, at May 29, 2006 9:04 AM  

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