Under Antarctica’s ice, Weddell seals produce ultrasonic vocalizations


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IMAGE: University of Oregon evolutionary biologist Paul Cziko examines the undersea cam throughout a dive at the National Science Foundation-funded McMurdo Oceanographic Observatory. The observatory, finished in 2017, lies …
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Credit: Image by Henry Kaiser

EUGENE, Ore.– Dec. 21, 2020– Weddell seals are chirping, whistling and trilling under Antarctica’s ice at sound frequencies that are inaudible to human beings, according to a research study group led by University of Oregon biologists.

2 years of recordings at a live-streaming undersea observatory in McMurdo Noise have actually recorded 9 kinds of tonal ultrasonic seal vocalizations that reach to 50 kilohertz. Human beings hear in the sonic variety of 20 to 20,000 hertz, or 20 kilohertz.

The discovery is detailed in a paper released online Dec. 18 ahead of print the Journal of the Acoustical Society of America

Weddell seals ( Leptonychotes weddelii), the world’s southernmost-ranging mammal, prosper under the continent’s sea ice, utilizing their big teeth to develop air shaft. They can dive to 600 meters searching for victim and stay immersed for 80 minutes. Scientists had actually initially determined 34 seal call types at sonic frequencies in 1982, connecting the noises to social interactions.

The research study’s lead author Paul Cziko, a going to research study teacher in the UO’s Institute of Ecology and Development, started taping the seals’ sonic-ranged vocalizations in 2017 after finishing the setup of the McMurdo Oceanographic Observatory. Employees at McMurdo Station, he stated, typically went to sleep listening to broadcasts of the seals’ sonic noises originating from listed below.

” The Weddell seals’ calls develop a nearly amazing, transcendent soundscape under the ice,” Cziko stated. “It truly seems like you remain in the middle of an area fight in ‘Star Wars,’ laser beams and all.”

Over the next 2 years, the observatory’s broadband digital hydrophone – more delicate than devices utilized in earlier recordings – got the higher-frequency vocalizations throughout passive tracking of the seals.

” We kept discovering these ultrasonic call enters the information,” stated co-author Lisa Munger, a marine biologist who studies marine mammal acoustics and a profession trainer in the UO’s Clark Formality College. “Lastly, it struck us that the seals were really utilizing them rather routinely.”

The 9 brand-new call types were made up of single or numerous singing aspects having ultrasonic basic frequencies. Eleven aspects, consisting of chirps, whistles and trills, were above 20 kHz. 2 went beyond 30 kHz and 6 were constantly above 21 kHz. One whistle reached 44.2 kHz and coming down chirps in another call type started at about 49.8 kHz. Harmonics, or the overtones, of some vocalizations went beyond 200 kHz.

” It was truly unexpected that other scientists formerly had, in impact, missed out on a part of the discussion,” stated Cziko, who made a doctorate in evolutionary biology from the UO in 2014.

What the ultrasonic vocalizations indicate in the Weddell seals’ collection is unidentified. The seals are amongst 33 types of fin-footed mammals organized as pinnipeds. Previously, pinnipeds, which likewise consist of sea lions and walruses, were thought to vocalize just at sonic levels.

It might be, Cziko stated, that the seals produce the noises just to “stick out over all the lower-frequency sound, like altering to a various channel for interacting.”

Or, the scientists kept in mind, the ultrasonic vocalizations might be utilized for echolocation, a biological finder that dolphins, toothed whales and bats utilize to browse in restricted presence to prevent barriers and find buddies or victim.

” The possibility of seals utilizing some type of echolocation has actually truly been marked down for many years,” Cziko stated. “We really had a great deal of rather heated conversations in our group about whether or how the seals utilize these ultrasonic noises for echolocation-like habits.”

It is not understood how Weddell seals browse and discover victim throughout the months of near outright darkness in the Antarctic winter season. The research study offers no proof for echolocation.

” We want to understand who is producing the ultrasonic calls– males, women, juveniles, or all of the above,” Munger stated. “And how are the seals utilizing these noises when they’re out in much deeper water, trying to find fish? We require to tape-record in more locations to be able to associate noises with habits.”

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Nick Santos of the Center for Infotech Research Study in the Interest of Society at the University of California, Merced, and John Terhune, teacher emeritus at the University of New Brunswick in Saint John, Canada, were co-authors. Santos crafted the data-collection pipelines for the observatory.

The National Science Structure mainly supported the research study through a grant to Cziko and Arthur L. DeVries, teacher emeritus at the University of Illinois at Urbana-Champaign who has actually performed research study considering that 1961 in Antarctica. DeVries found the biological antifreeze that permits fish to make it through in seawater at temperature levels at and simply listed below freezing.

Associated Hyperlinks, consisting of to videos and images:

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McMurdo Oceanographic Observatory: https://moo-antarctica.net/

About Paul Cziko: http://www.paulcziko.net/

About Lisa Munger: https://honors.uoregon.edu/lisa-munger

UO Institute of Ecology and Development: https://ie2.uoregon.edu/

Opening a Window on Life Under Antarctica: https://around.uoregon.edu/antarctica

The research study group’s video summary of the research study: https://youtu.be/jmZ8uLwyxIo

The brand-new ultrasonic call types: https://youtu.be/bqk4nOcbxnY

Observatory recording of a seal ultrasonic call: https://youtu.be/NE-sNx1R2L4

Images of the observatory and Weddell seals: https://www.dropbox.com/sh/nycl0muisi0xvyx/AACe36NHa5G5P_xUAkkAjD0ga?dl=0 .

Disclaimer: AAAS and EurekAlert! are not accountable for the precision of press release published to EurekAlert! by contributing organizations or for using any info through the EurekAlert system.



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