With underwater microphones, scientists recorded the sounds the fish made when they confronted one another.
They reported in the Journal of Experimental Biology that each of these three sounds appeared to contain a different "message".
The other two were a drum-like percussive beat, which piranhas produced when they chased one another, and a softer croak they made when biting each other. Most of the time, though, the fish swam around peacefully, making no noise and engaging in none of these underwater conflicts.
It was only through hours of painstaking observation that the researchers managed to capture the behaviour.
Finally, I pulled my car on the road side to ask for help from people who drove by me.
A woman saw me sticking out my head through the car window, so she yelled at me because it was too dangerous and unsafe.
Business class passengers used to traveling with hand luggage only and who are in a hurry while at the same time being very well-informed, do not expect to be offered trivialized support designed to pander to larger numbers of passengers.
She even asked me to follow her until I came to the right place. Ill never forget the most intimidating experience of my life. I was going to friends house a couple of months ago. After driving a few more kilometres in a local area I realized that I was driving towards another city.
Despite a nasty reputation, piranhas seem to bark more often than bite.
Scientists have discovered that the fearsome fish use sounds to communicate - often intimidating their rivals rather than attacking.
Facebook App: Open links in External Browser There is a specific issue with the Facebook in-app browser intermittently making requests to websites without cookies that had previously been set.
This appears to be a defect in the browser which should be addressed soon.