(Press-News.org) 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
THIS ARTICLE IS EMBARGOED UNTIL THURSDAY, 22 March 2012, 00.15 HRS EDT (04:15 HRS GMT)
END
Tapping out a beat may help children learn difficult fraction concepts, according to new findings due to be published in the journal Educational Studies in Mathematics. An innovative curriculum uses rhythm to teach fractions at a California school where students in a music-based program scored significantly higher on math tests than their peers who received regular instruction.
"Academic Music" is a hands-on curriculum that uses music notation, clapping, drumming and chanting to introduce third-grade students to fractions. The program, co-designed by San Francisco State ...
NEW YORK ( March 22, 2012) - Mothers' exposure during pregnancy to a class of air pollutants called
polycyclic aromatic hydrocarbons (PAH) can lead to behavioral problems in their children. PAH are
released to air during incomplete combustion of fossil fuel such as diesel, gasoline, coal, and other
organic material.
The study is the first report of associations between child attentional and behavioral problems among school‐age children and two complementary measures of prenatal PAH exposure: monitored air concentrations of PAH and a PAH-specific biomarker of exposure ...
March 22, 2012, New York, NY—As the second anniversary of the Affordable Care Act approaches, a new Commonwealth Fund report finds that 49 states and the District of Columbia have already taken action supporting the law's implementation, such as passing legislation, issuing regulations or other guidance, or actively reviewing insurer filings. Early insurance market reforms in the law include new rules for insurers such as bans on lifetime limits on benefits and dependent coverage for young adults up to age 26.
The report, Implementing the Affordable Care Act: State Action ...
AUGUSTA, Ga. – More than 75 percent of fourth-graders in urban and rural settings have measurable levels of a nicotine breakdown product in their saliva that documents their second-hand smoke exposure, researchers report.
A study of 428 fourth graders and 453 parents in seven rural and seven urban Georgia schools also showed that the urban children were more likely to be smokers – 14.9 percent versus 6.6 percent. Additionally urban children have the most exposure to smokers: 79.6 percent versus 75.3 percent, according to findings presented to the 15th World Conference ...
The new PIE-1 Alarm IP Encoder from Optex provides the dual functions of PoE power delivery to remote Optex devices and conversion of alarm signals to an IP protocol for delivery to video management systems or network video recorders. The PIE-1 provides support for Optex sensors in security systems using VMS and NVRs through vendor- unique API.
The device can be used in a number of ways:
- PoE (Power over Ethernet) only: to power remotely the Optex Redscan laser scanner provides IP alarm signals natively and requires no conversion encoding. The PIE-1 supports both ...
"Erik Orsenna, dictator of grammar! Look, you're killing the French language!" the rapidly-becoming viral video went (OK, viral by French not American standards).
Then the number 2 magazine group of France called "Le Nouvel Obs" picked up the story as did many literary websites (see attachments on right-hand side of this text.)
Some of these press releases start with those very same angry words, the aggressive words pronounced by the author on the video against French grammar.
The problem is that the author on the video is in fact an American ...
HOLLYWOOD, Fla. (March 18, 2012)—People are living longer with and after a cancer diagnosis, making survivorship clinics and programs—as well as official guidelines and practices governing the care of survivors—an important emerging component of modern cancer care. Many institutions are looking to gather these resources into an easily understandable plan for their survivors.
"Cancer survivors face a lot of unique and very specific challenges," says Crystal S. Denlinger, M.D., a medical oncologist at Fox Chase Cancer Center who will present on best practices in cancer ...
A research team led by the University of Melbourne, Australia, has developed a novel technique that tracks diseased proteins behaving badly by forming clusters in brain diseases such as Huntington's and Alzheimer's.
The technique published in Nature Methods today is the first of its kind to rapidly identify and track the location of diseased proteins inside cells and could provide insights into improved treatments for brain diseases and others such as cancer.
Developed by Dr Danny Hatters and his team of the Department of Biochemistry and Molecular Biology at the ...
Statins may prevent pneumonia, according to a new study in CMAJ (Canadian Medical Association Journal). Researchers from Israel and the United States analyzed data from the JUPITER trial, a randomized, double-blind trial with placebo control groups conducted at 1315 sites in 26 countries to look at the use of the statin rosuvastatin in disease prevention. The trial involved 17 802 men aged 50 years or older and women aged 60 years or older without a history of heart disease or diabetes.
Patients were randomized to receive either a placebo or rosuvastatin, a statin used ...
Blood testing to determine a link between food and illness is increasingly common, but some tests are not considered diagnostic and can lead to confusion, according to a primer in CMAJ (Canadian Medical Association Journal).
Both traditional physicians and holistic medicine practitioners may offer blood testing to diagnose adverse reactions to food. A food allergy is a specific immunologic reaction to a food that can be reproduced with exposure to the food in question. An intolerance is an adverse reaction without an immunologic response, such as lactose intolerance. However, ...
