Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

False killer whales use acoustic squint to target prey

22.03.2012
False killer whales focus echolocation clicks

Hunting in the ocean's murky depths, vision is of little use, so toothed whales and dolphins (odontocetes) rely on echolocation to locate tasty morsels with incredible precision. Laura Kloepper from the University of Hawaii, USA, explains that odontocetes produce their distinctive echolocation clicks in nasal structures in the forehead and broadcast them through a fat-filled acoustic lens, called the melon.

'Studies by other people showed odontocetes have the ability to control the shape of the echolocation beam and it has always been assumed that they are using the melon to focus sound' explains Kloepper. However, no one had ever tested this directly, so Kloepper and her PhD supervisor, Paul Nachtigall, decided to tackle the question. They publish their discovery that false killer whales are able to focus their echolocation beams on targets in The Journal of Experimental Biology at http://jeb.biologists.org.

So, how did the team make this amazing discovery? Fortunately, the duo is based at the Marine Mammal Research Program at the University of Hawaii, which is home to Kina the false killer whale. Kloepper explains that Kina is extremely adept at working with marine biologists after decades of dedicated work by Marlee Breese and her training staff. On this occasion, Kina had been trained to recognise a 37.85-mm-wide cylinder with 6.35-mm-thick walls by echolocation, signalling that she had recognised the cylinder by touching a button in return for a fish reward. However, when Kina encountered other cylinders – with different wall thicknesses – she was trained to remain still before receiving her fishy prize. The team then selected two other cylinders to test her echolocation abilities:

one with much thicker walls (7.163mm) that Kina could detect with ease and another with only marginally thicker walls (6.553mm) that Kina had more difficulty distinguishing from the 6.35mm cylinder. Then, over a period of weeks, Nachtigall, Breese and Kloepper randomly presented the cylinders to Kina at distances ranging from 2.5 to 7m, while noting her success rate and recording the cross-sectional area of her echolocation clicks with an array of hydrophones located between her and the cylinder.

But there was a problem: the width of an acoustic beam is determined by the frequency of the sound. So how could the team tell whether a change in beam width was due to Kina focusing the sound or simply due to the physics of acoustics? They turned to statistician Megan Donahue. 'Using statistics, we can account for the natural relationship that exists between beam area and frequency', says Kloepper, allowing them to correct for the frequency-related beam width variation. Plotting the adjusted beam area against the distance to the target, Kloepper discovered that Kina's echolocation beam became wider when she was having difficulties distinguishing between the 6.553mm and 6.35mm cylinders and when the cylinders were more distant. The false killer whale was effectively 'squinting' and adjusting the size of her echolocation beam in response to the more difficult tasks.

But was she actually focusing on the objects, because the beam width seemed to be getting wider rather than focusing in? Kloepper realised that the beam only appeared wider at the cluster of hydrophones because the array was close to Kina. When she plotted the path of the acoustic beams as they emerged from the animal's melon and passed through the hydrophone array, it was clear that the beams that appeared widest at the hydrophones were focused furthest away while the narrowest beams must be focused on the nearest objects.

'This is the first time that someone created a basic design to show that there is differential focusing of the beam under different target and echolocation conditions', says Kloepper, who is keen to find out whether other species use Kina's focusing strategy.

IF REPORTING ON THIS STORY, PLEASE MENTION THE JOURNAL OF EXPERIMENTAL BIOLOGY AS THE SOURCE AND, IF REPORTING ONLINE, PLEASE CARRY A LINK TO: http://jeb.biologists.org/content/215/8/1306.abstract

REFERENCE: Kloepper, L. N., Nachtigall, P. E., Donahue, M. J. and Breese, M. (2012). Active echolocation beam focusing in the false killer whale, Pseudorca crassidens. J. Exp. Biol. 215, 1306-1312.

This article is posted on this site to give advance access to other authorised media who may wish to report on this story. Full attribution is required, and if reporting online a link to jeb.biologists.com is also required. The story posted here is COPYRIGHTED. Therefore advance permission is required before any and every reproduction of each article in full. PLEASE CONTACT permissions@biologists.com

Kathryn Knight | EurekAlert!
Further information:
http://www.biologists.com

More articles from Life Sciences:

nachricht Transport of molecular motors into cilia
28.03.2017 | Aarhus University

nachricht Asian dust providing key nutrients for California's giant sequoias
28.03.2017 | University of California - Riverside

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>