Navigation Links
Koalas' bellows boast about size
Date:9/28/2011

Koalas have a well-earned reputation for being dopey. Sleeping 19 hours out of every 24, and feeding for 3 of the remaining 5 hours, there doesn't seem to be much time for anything else in their lethargic lifestyle: that is until the mating season. Then the males begin bellowing. Benjamin Charlton from the University of Vienna, Austria, explains that they probably bellow to attract females and to intimidate other males. But what messages could these rumbling bellows communicate about their senders? Charlton and an international team of collaborators publish their discovery that the koalas are boasting about their size in the Journal of Experimental Biology at http://jeb.biologists.org.

According to Charlton, they could be telling nearby listeners about their size. He explains that there was a possibility that koalas may be one of the few animals that have a descended larynx, which makes the vocal tract longer. Also, because all pipes including vocal tracts have frequencies where the air inside them vibrates naturally and amplifies sound, larger animals with longer vocal tracts produce lower resonances, giving their voices a more baritone quality. So, the longer vocal tracts of the largest koalas should produce deeper resonances to tell the listening koala audience just how big they are. Intrigued, Charlton, Tecumseh Fitch and their colleagues decided to find out whether male koalas have descended larynxes.

Teaming up with Allan McKinnon at Moggill Koala Hospital and Gary Cowin and William Ellis at the University of Queensland, Australia, Charlton investigated the anatomy of the marsupial's vocal tract. Using MRI and post-mortem studies, the team found that the koala's larynx had descended to the level of the 3rd and 4th cervical vertebrae, instead of being high in the throat. They were also surprised to find that the muscle that attaches the larynx to the sternum was anchored very deep in the thorax and they suggest that it could be involved in pulling the larynx even further down into the chest cavity.

But what effect does the koala's deeply descended larynx have on the acoustics of their bellows? Travelling to the Lone Pine Koala Sanctuary, home to 140 koalas, Charlton patiently recorded their rumbling bellows. He also measured the animals' head sizes, with the help of Jacqui Brumm and Karen Nilsson, as skull size is a good proxy for body size.

Back in the lab, Charlton analysed the bellows' spectra and found that the largest males always had lower resonances than the smaller animals. More surprisingly, when Charlton calculated the koala's vocal tract length based on their acoustics, he was astonished to find that the koalas were able to make themselves sound as if they had 50-cm-long vocal tracts, nearly the entire length of the animal. In fact, the diminutive animals sound even larger than bison. Charlton suspects that koalas use the resonances of the oral and nasal tracts simultaneously to sound much larger than they are.

So, koala males are able to communicate their size, with the largest animals producing the richest baritone bellows. Charlton also suspects that the males' boastful bellows could have driven the evolution of their descended larynxes. 'Individuals that could elongate their vocal tracts by lowering the larynx may have gained advantages during sexual competition by sounding larger, and this would drive the evolution of laryngeal descent,' he says.


'/>"/>
Contact: Kathryn Knight
kathryn@biologists.com
44-078-763-44333
The Company of Biologists
Source:Eurekalert

Related biology news :

1. Loud and lazy but didnt chew gum: Ancient koalas
2. What can magnetic resonance tractography teach us about human brain anatomy?
3. New approach challenges old ideas about plant species and biomass
4. Scientists concerned about pesticide education funding
5. Clemson University peach specialist unveils CaroTiger, something to roar about
6. Interventional radiologists: Learn about peripheral arterial disease and get moving
7. BUSM professor authors book on how knowledge about genes and family history can save lives
8. Not so fast -- researchers find that lasting evolutionary change takes about 1 million years
9. No bones about it: Eating dried plums helps prevent fractures and osteoporosis
10. Paranoia about rivals alters insect mating behavior
11. UNC-Duke ties lead to collaborative finding about cell division & metabolism
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/19/2017)... York , April 19, 2017 ... as its vendor landscape is marked by the presence ... market is however held by five major players - ... Together these companies accounted for nearly 61% of the ... the leading companies in the global military biometrics market ...
(Date:4/17/2017)... , April 17, 2017 NXT-ID, Inc. (NASDAQ: ... announces the filing of its 2016 Annual Report on Form 10-K ... Commission. ... 10-K is available in the Investor Relations section of the Company,s ... the SEC,s website at http://www.sec.gov . 2016 Year ...
(Date:4/13/2017)... , April 13, 2017 According to a ... Identity Authentication, Identity Analytics, Identity Administration, and Authorization), Service, Authentication Type, Deployment ... the IAM Market is expected to grow from USD 14.30 Billion in ... Rate (CAGR) of 17.3%. ... MarketsandMarkets Logo ...
Breaking Biology News(10 mins):
(Date:4/24/2017)... -- Dante Labs announced today the offer of whole genome sequencing ... American individuals have been able to access WGS at $1,000, ... below EUR 1,000. The sequencing includes bioinformatics analysis ... make informed decisions about disease monitoring, prevention, nutrition, exercise, health ... ...
(Date:4/21/2017)... ... April 21, 2017 , ... Having worked on the ... Formaspace is pleased to introduce it to top lab design architects from around the ... Turk and VP of Industrial Design and Engineering Greg Casey will be at the ...
(Date:4/21/2017)... (PRWEB) , ... April 21, 2017 , ... ... and related applications were the focus of researchers, engineers, product developers, and industry ... in Anaheim. , Sponsored by SPIE, the international society for optics and ...
(Date:4/21/2017)... ... April 21, 2017 , ... Frederick Innovative Technology Center, Inc. ... bio and technology start-ups, is hosting “Celebration Friday” (a festive gathering highlighting client ... with libations and networking at 3:30 p.m. at FITCI’s 4539 Metropolitan Court location, ...
Breaking Biology Technology: