The terrifying image with sharp as the blade teeth, predatory nature - it’s not all associations that occur in people with the word "piranha", now to the list of associations can also add a ferocious "bark" of predatory fish. Aggressive piranhas krasnobryuhie capable of reproducing sounds like barking, scaring, so other piranhas, a new analysis of the show.
Researchers from the University of Liege in Belgium, noted that krasnobryuhie sinister piranhas (Pygocentrus nattereri), make sounds like barking when caught and lifted out of the water people. In order to find out why and how this happens, the research team found a hydrophone in the water tank, which contained the piranhas and record any sounds that they made throughout the day. Researchers also filmed the fish in the video, so that later had the opportunity to combine the recorded sounds with a length videos. The resulting record showed that fish were generally non-corrosive and quiet. But it was necessary only to two or more of the fish face, the silence gave way to a wild barking.
Watching piranhas swimming in a water tank and competing for food, the researchers noticed that the fish reproduces three distinct martial sound. The first was something like the bark which they made during the so-called frontal clashes when two Piranhas swim quickly to each other and stay face to face. "That sound, therefore, was interpreted as an alarm, which is equivalent intimidating phases in a conflict situation between two individuals" - the researchers noted in the current issue of the journal "Journal of Experimental Biology". It was like the same bark which researchers heard when caught a piranha.
The second sound was described as a short, percussive sound like a drum, which published the fish in the fight for food, swimming in circles around his opponent. The third type of sound has been described as a weak "croaking" which they made their jaws, snapping at each other.
In the previous study, it was found that piranhas reproduce the sounds using the muscles attached to their swim bladder, but scientists did not know until the end how the swim bladder is involved in the production of sounds. In order to figure out that the researcher Eric Parmentier (Eric Parmentier) and his research group called the swim bladder contraction krasnobryuhih piranhas by his promotion.
The results showed that the bubble ceased to vibrate as soon as the muscles ceased to decline. This meant that the muscles directly ruled by the vibrations of the swim bladder, as the researchers reported. The frequency of barking and drum sounds have been identified contraction of muscles, and not by any sound properties of the swim bladder. Despite the fact that the piranha-fed behaved relatively peacefully, they occasionally attacked each other, and even biting his fingers for researchers.
"Some members of our group had to go to the hospital because they had been bitten, and the finger of one of his colleagues had been cut by almost half" - said Parmentier. But despite this fact, the encyclopedia Encarta, and other sources say that the stories about the piranhas attack on the people - a hoax. Fish are known to feed on worms and small fish.
"As long as there were no documented deaths due to piranha attacks on humans," as reported in Encarta. "To conduct this predatory fish characterized otschipyvanie parts of fins or scales of other fish species. This tactic allows you to crop the victim to survive and rebuild the damaged parts, providing a certain type of food the updated resource for piranhas."
Parmentier said that now the goal of researchers will study the characteristics of the sound capabilities of fish during mating. Scientists will have to make a trip to Brazil to their water piranhas for new discoveries, since the fish are not able to play in a container with water.
Original: LiveScience Translation: M. Potter