Scientists form the University of Liege in Belgium constructed a mechanism to try and explain why barking occurs. By means of close observation in a tank with piranhas, researchers discovered that this baking is displayed as an aggressive and combative behavior towards a fellow piranha who makes "face to face" interaction. It is more or less a sick game of chicken as the piranhas bark furiously while swimming rapidly towards each other. Barking, however, was not the only behavior that was observed.
**To hear a sample clip of this barking, please click on the smiley face --> :) **
Two other combative sounds were recorded with the hydrophone (under-water microphone) and the actual behavior was observed in a parallel video recording. By using this method, the researchers were capable to go back and analyze the sounds and correlating behaviors of the fish at their own leisure. The second sound was a quick drum-like percussion sound. This was given off when fish were fighting over the same source of food. The final sound observed was that of a croaking sound that was exhibited as the red-bellied piranhas would snap their jaws at one another in a fierce and threatening manner.
These interactions amongst these members of the same species portrays the struggle for survival and may seem to cast an even darker shadow on the likability of these fish. Nevertheless, it should be known that piranhas are actually very peaceful and silent creatures... stick your finger in their face however, well let's just say you deserve what's coming to you.
For a visual of Pygocentrus nattereri, simply click on its latin name :p
Original article location: http://www.msnbc.msn.com/id/44890741/ns/technology_and_science-science/#.TpdKseAv0TP
By Jose Mijangos
This is very interesting, as i has no idea that piranhas were vocal creatures at all! I agree that the media has gave these animals a bad rep, and people should be more educated about them before they begin passing judgments. It is obvious that this form of communication is beneficial to their survival,as vocalized aggression is much less costly than physical aggression. I wonder if this bark is found in other species of piranhas as well, and whether have different variations of it. I also wonder if this bark is innate or learned. I would be interested in seeing further research on this topic, and see how their communication compares to other species.
ReplyDeletePosted by Sara Corey
This barking could possibly be used to prevent a piranha attack. If someone enter water with piranha in it played the barking sound, it may attract but ultimately repel the fish. They'd come to see the source, but not fully approach, as it seems that this use of signalling prevents escalation.
ReplyDeleteBy Joseph Needleman
This post gave me the chills! All these sounds that are made seem to be made in a state of aggression. I wonder if they make noises that we cannot hear in other contexts. It seems like their bark is at a very low frequency, so maybe their less threatening calls, such as calls for mating, would tend to be of a higher frequency, undiscovered by the humans. I enjoyed the song clip attached, thank you for that. It makes it much more interesting to hear what you are reading about.
ReplyDeletePosted by Abbie Saranteas
I wonder if their large repertoire of combative sounds prevents them from fighting as much as they would if they were unable to communicate. It seems like their barking might be related to defense of territory, and the drumming and croaking sounds are used to prevent fights over food. Yes, obviously these sounds support the view that piranhas are aggressive fish, but the purpose of these sounds is essentially to try and minimize the number of fights that actually occur, which is a pretty neat survival technique.
ReplyDeletePosted by Johanna Brophy
I'm glad to see that my entry sparked the interest of a number of people! I will respond to each comment in their respective order... Sara, you are absolutely correct in stating that this vocalization is more energy efficient than is actually physical aggression. I believe this is the key reason which gave through to the evolution of such form of communication. Also, I'm sure that other variations of this bark exist in other species of piranhas and I believe this behavior is innate, but like most other behaviors, it is perfected through imitation of older members in its school.
ReplyDeleteJoseph, I can see where your coming from in saying that perhaps the red-bellied piranhas use this bark to attract a certain type of attention. It may play as "bait" for other fish when foraging. What the researchers concluded from their experiment was that this bark was ultimately used as a warning signal for neighboring organism to keep back, but we have come to learned in class that one signal can be used to interpret quite an array of intended messages.
Abbie, this bark is indeed used in states of aggression and are observed to be at very low frequencies. I would imagine that their mating calls are at much higher frequencies, although this particular experiment did not record any. The reason being that this research was conducted in Belgium and piranhas are known to return to their natal waters of Brazil exclusively to mate. It would be interesting to hear and compare the differences between the combative bark and a piranhas mating calls. And as far as the sound input, your very welcome! :) I find it very helpful to have a acoustic and/or visual stimulation to keep both the writer and his/her reader more engaged and hopefully make their entry that much more enjoyable.
And last but most certainly not least, Johanna, you brought an interesting point. The fact that this species of piranha is capable of such vocalization serves as a vital and effective way to minimized physical confrontation between members of its same species. I could only but imagine witnessing the scene of red-bellied piranhas fighting over a source of food and hearing the drumming noise... must be spine-chilling!!
Thank you very much for taking the time to read my post and more over, actually posting a comment. It is greatly appreciated. This is actually my first official scientific blog post and seeing that I had comments was an exhilarating feeling. Thanks again!
Response by Jose Mijangos
This article was great and made me realize that just from hearing things from other people saying that piranhas are very aggressive all the time, doesn't mean it is true. If you aggravate anything, it is going to try to defend itself. Do the piranhas bark when they are looking for a mate? Or is it just in times of aggression and self defense?
ReplyDeletePosted by Ryan Dulmaine
This particular behavior was only demonstrated in situations of aggression and combat. However, this information is limited by the one study. As it was mentioned before, this behavior/means of communication may be observed in other contexts outside of this work. Perhaps the bark itself is not the mating call considering it is at such a low frequency, but then again, there are always exceptions to every generalization. Thank you for commenting! :)
ReplyDeleteResponse by Jose Mijangos
Yes the good name of the piranha has been dragged through the mud. As I read this I was just curious if the article mentioned whether or not this "bark" was within the audible frequency range for humans. It just seems strange that no one has ever noticed this curious behavior before.
ReplyDeletePosted by Michael Thomas
Actually Michael, this barking behavior was first observed when a fisherman literally picked up a red-bellied piranha. This is what initially gave way to this study and lead to the discovery of the other two vocalizations. As it appears this was a new line of research conducted on this type of behavior for this species. This kind of make me want to watch that new "Piranha" thriller to see if they integrate such behaviors. -well, kind of. Or not -_- Thank you for commenting though!
ReplyDeleteResponse by Jose Mijangos