Sounds emitted by sharks are first recorded; listen

Sharks have a reputation for being silent killers – the main ocean predators are stealthy hunters, but they also lack sound producing organs found in many other fish. Now, a new innovative study has revealed that a kind of shark can be more vocal than it was thought earlier, producing sounds comparable to the burst of a balloon.

For the first time, scientists recorded evidence of the cation-cation-de-care-Mustelus lenticulatus-actively producing sound by hitting their teeth, according to a survey published on Tuesday (25) in the magazine Royal Society Open Science.

“Since sharks maintain social groupings or communicate was considered mainly through body language and possibly through chemical signs; but largely remained a mystery,” said Neil Hammerschlag, president of Atlantic Shark Expeditions and executive director of Shark Research Foundation, a non-profit organization that aims to increase knowledge and promote sharks. Hammerschlag did not participate in the research. “This study opens a totally new possibility of communication via sound.”

The cation-cation-de-care, a small species that inhabits the coastal waters of New Zealand, typically lives near the seabed and plays a key role in the region’s commercial fishing industry. Unlike most fish that depend on a swim bladder – a gas -filled organ that helps fish maintain their float and produce and detect sound – sharks do not have this feature, making sound production seemingly unlikely.

The main author of the study, Carolin Nieder, began to be interested in the acoustic capabilities of sharks after hearing an unexpected click sound during behavioral training experiments while doing his doctorate at Auckland University in 2021. Nieder is currently postdoctoral researcher at T. Aran Moononey at the Woods Hole Oceanographic Institute in Massachusetts.

Although I could not investigate the mysterious click at the time, the interest remained. Now, Nieder and his team have reported fascinating discoveries of the study with 10 juvenile cations-five males and five females-captured on the coast of New Zealand.

Making some noise

Scientists maintained sharks in large marine laboratory tanks, with adequate sea water and food conditions, from May 2021 to April 2022.

To carefully record any sounds issued, the team has transferred sharks to individual tanks equipped with subacket or hydrophones. When the sharks were moved between tanks or kindly insured, they began to make click sounds, similar to those Nieder had noticed years earlier.

Each click was extremely short, lasting an average of 48 milliseconds, faster than a blink of human eyes.

The researchers also identified the clicks as broadband, meaning that they occurred in a wide range of frequencies of 2.4 to 18.5 kilohertz – some of which can be detected by humans, according to the study.

In terms of volume, the clicks were intense, reaching about 156 decibels.

The study noted that most clicks occurred in the first 10 seconds of manipulation, becoming less frequent over time. During the initial 10 seconds, sharks issued an average of seven clicks compared to the final 10 seconds with an average of only two clicks.

“As the animals got used to the daily experimental protocol, they completely stopped clicking, as if they were used to captivity and experimental routine,” Nieder said by email. “This led us to consider that we may be observing sound production behavior rather than a strange artifact.”

Cation-cation

The team also noted that about 70% of the clicks occurred when the shark slowly shook side by side, while about 25% of clicks happened when the shark displayed explosive movements, swinging the head or body. Only 5% of the movements happened when the shark was not obviously moving his body, according to the study.

What is causing the crack of the cations-cations-de-studio?

With no organs specializing in sound production found in these sharks, researchers are confident that clicks come from their strong and interconnected teeth hitting each other.

These plate -shaped teeth, designed to crush prey as crustaceans, may be responsible for producing the distinctive click sound, similar to the sounds some fish make their teeth when grinding.

The consistent standard and frequency of clicks also suggest that the sounds are intentional instead of accidental, Nieder said.

Researchers are still trying to investigate why exactly the cation-cation-de-care issues these sounds. One possibility is that clicks serve as a sign of anguish, which could be a reaction to handling during the experiment.

Most clicks were out of the hearing band of the casualties themselves, which extends to about 800 Hertz, according to the study. If sharks are not using their vocal capabilities to communicate with each other, clicks may serve as a warning sign or form of aggression around prey or in dangerous situations, the researchers wrote.

Vocal skills in natural habitats

With over 500 shark species around the world, it is still unclear whether other sharks share this ability to produce sound.

“I believe there is a chance that other sharks are making similar sounds,” said Nieder. “This documentation can help us start listening to sharks, and maybe we can learn more interesting things about their ecology and lifestyle in their various ecological niches.”

In addition, as the sounds were recorded in a controlled laboratory environment, researchers are eager to find out if the cations-stewards also produce these noise in nature and in what conditions.

“This study opens the possibility of these smaller sharks” sounding the alarm, “Hammerschlag said by email, referring to how smaller sharks disperses in the presence of larger sharks, even if they are out of sight. “Although we do not really know if the sound produced by the cations-cations-de-stew was simply a byproduct of handling … This opens some new questions, possibilities and ways for future research.”

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This content was originally published in sounds issued by sharks are first recorded; Listen to the CNN Brazil website.

Source: CNN Brasil