Featured Research

from universities, journals, and other organizations

Aggressive piranhas bark to say buzz off

Date:
November 1, 2011
Source:
Journal of Experimental Biology
Summary:
Piranhas are best known for their bite, but did you know they make sounds too? A team of researchers knew that piranhas could produce at least one sound, but they didn't know when and why the fish become vocal. Filming and recording sounds produced by piranhas competing for food, they found that the fearsome fish have a repertoire of three sounds to threaten competitors.

Piranhas.
Credit: © Kevkel / Fotolia

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 Liθge, 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.

The research appears in The Journal of Experimental Biology.

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.


Story Source:

The above story is based on materials provided by Journal of Experimental Biology. The original article was written by Kathryn Knight. Note: Materials may be edited for content and length.


Journal Reference:

  1. Sandie Millot, Pierre Vandewalle, Eric Parmentier. Sound production in red-bellied piranhas (Pygocentrus nattereri, Kner): an acoustical, behavioural and morphofunctional study. Journal of Experimental Biology, 2011; 214 (21): 3613-3618 DOI: 10.1242/jeb.061218

Cite This Page:

Journal of Experimental Biology. "Aggressive piranhas bark to say buzz off." ScienceDaily. ScienceDaily, 1 November 2011. <www.sciencedaily.com/releases/2011/10/111013085232.htm>.
Journal of Experimental Biology. (2011, November 1). Aggressive piranhas bark to say buzz off. ScienceDaily. Retrieved April 18, 2014 from www.sciencedaily.com/releases/2011/10/111013085232.htm
Journal of Experimental Biology. "Aggressive piranhas bark to say buzz off." ScienceDaily. www.sciencedaily.com/releases/2011/10/111013085232.htm (accessed April 18, 2014).

Share This



More Plants & Animals News

Friday, April 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Great British Farmland Boom

The Great British Farmland Boom

Reuters - Business Video Online (Apr. 17, 2014) — Britain's troubled Co-operative Group is preparing to cash in on nearly 18,000 acres of farmland in one of the biggest UK land sales in decades. As Ivor Bennett reports, the market timing couldn't be better, with farmland prices soaring over 270 percent in the last 10 years. Video provided by Reuters
Powered by NewsLook.com
Flamingo Frenzy Ahead of Zoo Construction

Flamingo Frenzy Ahead of Zoo Construction

AP (Apr. 17, 2014) — With plenty of honking, flapping, and fluttering, more than three dozen Caribbean flamingos at Zoo Miami were rounded up today as the iconic exhibit was closed for renovations. (April 17) Video provided by AP
Powered by NewsLook.com
Change of Diet Helps Crocodile Business

Change of Diet Helps Crocodile Business

Reuters - Business Video Online (Apr. 16, 2014) — Crocodile farming has been a challenge in Zimbabwe in recent years do the economic collapse and the financial crisis. But as Ciara Sutton reports one of Europe's biggest suppliers of skins to the luxury market has come up with an unusual survival strategy - vegetarian food. Video provided by Reuters
Powered by NewsLook.com
Could Even Casual Marijuana Use Alter Your Brain?

Could Even Casual Marijuana Use Alter Your Brain?

Newsy (Apr. 16, 2014) — A new study conducted by researchers at Northwestern and Harvard suggests even casual marijuana use can alter your brain. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins