Bowhead whales are truly metal. They can live over 200 years, grow up to 60 feet long, and use their large, thick skulls to hurl their bodies through 8-inch-thick sea ice into the air above Arctic waters. But these tough creatures have a softer side, reported researchers on Tuesday. New audio recordings of the whales reveals that they make jazz.

“If humpback whale song is like classical music, bowheads are jazz,” lead author and University of Washington oceanographer Kate Stafford, Ph.D. explained in a statement about the new Biology Letters study on Tuesday. In the study, she and her team report they’ve produced the largest set of recordings of bowhead whales, consisting of audio gathered from 2010 to 2014 that includes 184 different songs. These diverse and vibrant recordings indicate that, despite the fact bowheads where almost hunted to extinction in the 1600s, this population is a healthy one. Check out a sample below, which sounds something like a mix between air escaping a balloon and a cat trying to get outside:

“The sound is more freeform,” she says, referring to the jazzy qualities of the sounds. “And when we looked through four winters of acoustic data, not only were there never any song types repeated between years, but each season had a new set of songs.” Using underwater microphones called hydrophones, her team recorded their massive compilation of whale songs, which indicates that bowheads sang many different songs 24 hours a day from November until April. These songs, which are described as having a “relentless variety” and “distinct musical phrases” continued in their vibrancy despite the fact they occurred during 24-hour darkness of the polar winter, under 95 to 100 percent sea ice cover.

That they are still singing is admirable in itself. Historically, bowhead whales have been the victims of human attacks: 500 years of commercial whaling left only 10,000 bowheads in the seas and placed them on the Endangered Species list. But Stafford’s collection of bowhead whale songs represents good news for the sea mammals, suggesting that the populations are robust and dynamic enough to continue singing their songs.

Nobody is really sure why bowhead whales are such good jazz children. Among the mysteries Stafford and her team still want to solve are whether it’s only males who can make the sounds, whether they can share songs, and why their tune changes constantly. Bowhead whale songs are much more varied than those humpback whales — the only other whale that sings elaborate songs — and are similar to the calls of birds like cowbirds and meadowlarks, which have a diverse array of calls, but scientists don’t know why.

What they do know is that in a 3-D habitat like the ocean, sounds like whale songs likely spread information about the location of food and, in some cases, has been shown help animals gossip. Still, that doesn’t give an explanation to the constantly changing blows of the bowheads. “Why are they changing their songs so much?” asks Stafford. “In terms of behavioral ecology, it’s a great mystery.”