Dolphin’s mouth. The whale sings. Fishcloak, chirp, Grant, ham, groans. However, in sea chatting, up until now, one voice was missing.
Sharks have long been considered quiet killers of the water. However, scientists at the University of Auckland in New Zealand recently recorded a rig shark, or Mastel Slenticratus, to create a sharp click by combining the teeth, according to findings published in the journal. Royal Society Open Science on Wednesday. They believe this is the first time a shark has actively made noise.
Chief investigator Karolyn Nieder was the first to hear the sound while studying the shark’s hearing abilities. While she was dealing with one shark, it clicked and snapped a similar sound to the sound of an electric spark, she said.
The noise came from the Rig shark, a rather small shark common in waters around New Zealand. It grows up to 5 feet and feeds mainly on crustaceans. It is eaten by larger shark species and New Zealanders who use it to make fish and chips.
Dr. Nieder was surprised when he heard the noise.
Other sea creatures have mechanisms to make noise. For example, fish have a gas-filled sac, a swimming bladder, which is used for buoyancy but can be used as a type of drum. Many fish have muscles that can vibrate the swimming bladder in a manner similar to the human vocal cords.
However, the sharks were “thought to be silent and could not actively produce sound,” Dr. Nieder said.
In this study, she and her co-authors observed the behavior of ten rig sharks housed in tanks equipped with underwater microphones. They discovered that all ten sharks begin to create click noise when they move between tanks or are held gently.
On average, the shark clicks nine times at 20-second intervals, and researchers believe they made noises by stitching the teeth together.
They didn’t make any noise while feeding or swimming, making scientists believe it is more likely to click when emphasizing or surprised, not as a way of communicating with each other.
“I think it’s likely that they’ll make those noises when they’re attacked,” Dr. Nieder said, adding that many other fish will snap their teeth and jaws to stop or distract predators.
It was unclear whether the shark could hear the clicks themselves. Did they make the sound in the wild or just get caught? And whether they intentionally made it or whether it was a side effect of their reaction to being surprised, Dr. Nieder said.
Christine Elbe, director of the Marine Science and Technology Centre at Curtin University in Australia, said the study expanded in the growing field of research into how marine animals make and hear sounds.
“Once you start watching, there are more and more species that use sounds,” she said.
So it wasn’t surprising to find that sharks could make a fuss, she said.
But she says, “I think it’s important in the sense that it completely underestimates communication between animals and environmental sensing capabilities, and also completely underestimates the way noise affects it.”
Source: www.nytimes.com
