Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Aggressive piranhas bark to say buzz off

13.10.2011
Thanks to Hollywood, piranhas have a bad reputation and it would be a brave scientist that chose to plunge their hand into a tank of them.

But that didn't deter Sandie Millot, Pierre Vandewalle and Eric Parmentier from the University of Liège, Belgium. 'You just have to pick them up and they make sounds,' says Parmentier. However, it wasn't clear when and why piranhas produce sounds naturally.

Intrigued by fish acoustic communication and the mechanisms that they use to generate sound, the team monitored the behaviour of small groups of captive red-bellied piranhas and publish their discovery that the fearsome fish have a repertoire of three combative sounds in The Journal of Experimental Biology at http://jeb.biologists.org.

Suspending a hydrophone in the piranhas' tank, Millot and Parmentier recorded the fish's sounds and filmed them as they cruised around and competed for food. According to Parmentier, the well-fed fish were relatively peaceful – attacking each other occasionally – although they were not averse to nipping at near-by fingers. 'We both visited the hospital because we were bitten and Sandie's finger was nearly cut in half,' recalls Parmentier.

Comparing the soundtrack with the movie, the team found that the fish were generally silent. However, they became quite vocal as soon as they entered into a confrontation – producing the same barking sound that they had produced when held in the scientists' hands. 'At first we thought there was only one sound,' admits Parmentier, but then it became apparent that the piranhas produce two more: a short percussive drum-like sound when fighting for food and circling an opponent; and a softer 'croaking' sound produced by their jaws when they snap at each other.

Having convinced themselves that the fish had a wider acoustic repertoire than they had initially thought, the team decided to find out how the fish produce the sounds.

Parmentier explains that piranhas were already known to produce noises using muscles attached to their swim bladders; however, it wasn't clear how the swim bladder was involved in sound production. So, the team stimulated the muscles to contract, measured the swim bladder's vibration and found that instead of resonating – and continuing to vibrate after the muscles ceased contracting – the swim bladder stopped vibrating as soon as the muscles finished contracting. In other words, the muscles were driving the swim bladder's vibration directly and the frequency (pitch) of the bark and drum sounds was determined by the muscles' contraction frequencies: not the swim bladder's own intrinsic resonant properties. They also found that the rear half of the swim bladder did not vibrate, so only the head portion of the swim bladder contributed to sound production.

Now that they have discovered that aggressive piranhas are quite vocal, the team is keen to find out whether amorous piranhas are vocal too. However, Parmentier suspects that the team will have to relocate to Brazil to answer that question. 'It is difficult for the fish to reproduce in the tank, so I am sure we have to deploy hydrophones in the field to have the sounds that are produced during mating,' says Parmentier.

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

REFERENCE: Millot, S., Vandewalle, P. and Parmentier, E. (2011). Sound production in red-bellied piranhas (Pygocentrus nattereri, Kner): an acoustical, behavioural and morphofunctional study. J. Exp. Biol. 214, 3613-3618.

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
http://jeb.biologists.org

More articles from Life Sciences:

nachricht Individual Receptors Caught at Work
19.10.2017 | Julius-Maximilians-Universität Würzburg

nachricht Rapid environmental change makes species more vulnerable to extinction
19.10.2017 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>