Mustelus lenticulatus
Scientists “picked up” the sound behavior for the first time, which only occurs when sharks are handled. There are three hypotheses on the table to explain why they do it.
After all, sharks are not frighteningly silent predators: they also make noises, and now, for the first time, we can hear them.
Sounds of high bursts were described in a study this Wednesday in the Royal Society Open Science. Even the authors were surprised by this news.
“I was very surprised,” he said Carolin downfrom the Woods Hole Oceanographic Institute, to: “It departed from the principle that sharks do not issue sounds.”
Scientists resorted to 10 copies of cation-cation-de-studio (Mustelus lenticulatus) -5 males and 5 females with 55.5 to 80.5 centimeters in length in New Zealand estuaries-and placed them in small tanks with underwater microphones.
When softly handled, each shark produced, in 20 seconds, short and high frequency clicks, with an average duration of 48 milliseconds and peak frequencies ranging from 2.4 to 18.5 kilohertz. THE intensity of these stalids – up to 166 decibels – is comparable to shoot a firearm or the explosion of a petard.
But the sharks only emitted these sounds when they upset them: they were silent when they were quiet, swimming and eating.
“At first, we thought it could be a strange artifact. But as animals got used to daily experimental protocol, they stopped making the stalids, as if they had used to being captive and experimental routine. This led us to consider that we may be observing sound production behavior and not a strange artifact,” Nieder explained.
How and why do it?
But how do these sharks make these noises? The most plausible hypothesis at this time for the investigators is that they close the jaws, causing their teeth to be very strong, but this has not yet been confirmed.
“Within the limits of the available data, the range of broadband frequencies and the short duration of platform clicks suggest Scented teeth during the quick closure of the mouth For sound production, ”explains the study.
And can they the ones themselves can hear the stalk they emit? This is another question yet unanswered. If they can’t, clicks can just be a involuntary reaction to stress and fright; if they can – and if other sharks can also – can the stalids be a form of communication.
There are still those who say that the sharks They are imitating the sound of Cameroonone of your favorite snacks to attract them.
“Scott Tindale (Tindale Marine Charitable Trust), who dedicates her life to sharks and other fish throughout New Zealand and Australia and who, by chance, listened to similar clicks of platforms in the wild, even before I noticed them, perhaps the platforms tried to imitate shrimps (part of their diet) to attract their burrows on their burrows Sedimento and then attack them. I think this is also a very interesting theory, ”said Nieder.
More and more proof that these cations are not the only ones to issue sounds. Investigators suspect that elasmobrans – The group of cartilage fish that includes sharks, rays and skates – may have sound abilities, contrary to popular belief.
Tomás Guimarães, Zap //
