Above water they sound like roaring Wookies. Under the ice they sound like chirping, chattering robots. Regardless, Antarctica’s Weddell Seals should have no trouble finding work in an upcoming Star Wars project.
“The Weddell Seals’ calls create an almost incredible, otherworldly soundscape under the ice,” said Paul Cziko, a visiting professor at the University of Oregon and lead author of a new study describing the bizarre seal noises, said in a statement. “It really sounds like you are in the middle of a space battle Star Wars, laser beams and all that. “
The catch: you would have to be an alien (or droid) to hear them; all those sci-fi sounds are totally inaudible to human ears.
Cziko and his colleagues were able to detect the alien sounds after two years of listening to Weddell seals (Leptonychotes weddellii) with a special hydrophone (an underwater microphone) installed in Antarctica’s McMurdo Sound in 2017.
Before the researchers started recording, scientists knew about 34 seal calls that are audible to human ears. Now, the team’s research – published online Dec. 18 in The Journal of the Acoustical Society of America – adds nine new types of ultrasound calls to the seal repertoire. Those sounds include trills, whistles, and otherworldly chirps, sometimes composed of multiple harmonized tones.
Humans hear in the sonic range of 20 to 20,000 hertz (or 20 kilohertz), the researchers noted. Most of the newly discovered seal noises exceeded 21 kHz, some as high as 30 kHz.
(McMurdo Oceanographic Observatory)
Above: a visual representation (spectrogram) of one of the nine types of ultrasonic calls. The U-shaped features in the top half of the field are part of call type U101.
A high-pitched whistle reached a screeching 49.8 kHz, the team wrote – and when seals harmonized multiple notes, the resulting sound could exceed 200 kHz. (That’s well beyond the hearing range of cats, dogs, and even some bats.)
What is all this high-frequency communication about? The researchers are not sure; Until now, scientists had never seen ultrasounds in seals (nor in other fin-footed mammals, such as sea lions or walruses).
A diver in McMurdo Sound in Antarctica observes a Weddell seal. (McMurdo Oceanographic Observatory)
According to Cziko, the sounds could just be bonus talk elements that “stand out above all the lower frequency sound, like switching to another channel to communicate.”
It is theoretically possible that the sounds are involved in echolocation, the biological sonar that animals such as dolphins and bats use to navigate dark places. But so far, there is no evidence that seals use echolocation, the researchers said.
Still, the behavior wouldn’t be strange for seals that can dive more than 600 meters underwater and hunt in the darkness of the Antarctic winter, the team added.
Let’s see how a Wookie tries that.
This article was originally published by Live Science. Read the original article here.