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 email@example.com
Kathryn Knight | EurekAlert!
Biophysicists reveal how optogenetic tool works
29.05.2020 | Moscow Institute of Physics and Technology
Mapping immune cells in brain tumors
29.05.2020 | University of Zurich
In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".
Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...
Early detection of tumors is extremely important in treating cancer. A new technique developed by researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The work is published May 25 in the journal Nature Nanotechnology.
researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from...
Microelectronics as a key technology enables numerous innovations in the field of intelligent medical technology. The Fraunhofer Institute for Biomedical Engineering IBMT coordinates the BMBF cooperative project "I-call" realizing the first electronic system for ultrasound-based, safe and interference-resistant data transmission between implants in the human body.
When microelectronic systems are used for medical applications, they have to meet high requirements in terms of biocompatibility, reliability, energy...
Thomas Heine, Professor of Theoretical Chemistry at TU Dresden, together with his team, first predicted a topological 2D polymer in 2019. Only one year later, an international team led by Italian researchers was able to synthesize these materials and experimentally prove their topological properties. For the renowned journal Nature Materials, this was the occasion to invite Thomas Heine to a News and Views article, which was published this week. Under the title "Making 2D Topological Polymers a reality" Prof. Heine describes how his theory became a reality.
Ultrathin materials are extremely interesting as building blocks for next generation nano electronic devices, as it is much easier to make circuits and other...
Scientists took a leukocyte as the blueprint and developed a microrobot that has the size, shape and moving capabilities of a white blood cell. Simulating a blood vessel in a laboratory setting, they succeeded in magnetically navigating the ball-shaped microroller through this dynamic and dense environment. The drug-delivery vehicle withstood the simulated blood flow, pushing the developments in targeted drug delivery a step further: inside the body, there is no better access route to all tissues and organs than the circulatory system. A robot that could actually travel through this finely woven web would revolutionize the minimally-invasive treatment of illnesses.
A team of scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart invented a tiny microrobot that resembles a white blood cell...
19.05.2020 | Event News
07.04.2020 | Event News
06.04.2020 | Event News
29.05.2020 | Materials Sciences
29.05.2020 | Materials Sciences
29.05.2020 | Power and Electrical Engineering