Humans have long been fascinated with narwhal tusks.

During the Middle Ages, the long, spiraled teeth -- mistaken for unicorn horns -- were the prized possessions of European royalty. And in the 19th century, they were featured in the writings of Charles Darwin and Herman Melville.

But, despite enduring interest, much remains unknown about the purpose of narwhals' tusks, largely because few people have seen them in action.

That is, until now. By flying drones over a remote stretch of the Canadian Arctic, scientists were able to capture unique footage of narwhals, shedding light on the function of their famed protuberances, according to a study published Feb. 27 in Frontiers in Marine Science.

"We had this window into their secret world," Greg O'Corry-Crowe, one of the study authors, told McClatchy News. "And thankfully they rewarded us with some amazing behavior."

Multiple behaviors were observed that indicate narwhal tusks -- like Swiss Army knives -- serve as multi-purpose tools. While they likely evolved for sexual selection (males use their tusks to compete for females), they also appear to be integral in hunting and play.

Hunting prey

The footage was collected during a 2022 field study off Somerset Island, an uninhabited island in the Nunavut territory. Narwhals, which are related to beluga whales, are found here and throughout other parts of Canada, Greenland, Alaska and Russia.

Over several days, drones were flown over a pod of narwhals swimming in the clear, coastal waters. One video revealed evidence of the marine mammals employing their tusks -- which can measure nearly nine feet long -- to hunt fish.

In the video, several narwhals can be seen speeding toward Arctic char -- a relative of salmon -- and striking them with their tusks.

"Hits sometimes involved side-to-side slashing of the tusk and resulted in stunning the fish," according to the study. At least one individual appeared to have successfully consumed a fish as a result of this method.

This behavior -- which had previously been recorded in 2016 -- could be indicative of a novel hunting strategy, O'Corry-Crowe, a professor at Florida Atlantic University, said.

"Tusks are mainly found in males," he said. "So if males are figuring out a new way to hunt prey, then it's interesting that that would be diverging from what females are doing ... Maybe having a long tusk gives you an advantage so you can catch up to (fish), hit it and slow it down."

He added that narwhals are known to hunt in the deep ocean, using suction in their mouths to capture squid, cod and shrimp.

"Are we starting to see them maybe feed on some other types of fish closer to the surface?" O'Corry-Crowe said.

But, the narwhals weren't the only predators present in the video. Glaucous gulls -- an Arctic species of seagull -- can be seen snatching fish that the marine mammals were pursuing, substantially reducing their success rate.

"The gulls appeared to have been tracking the narwhal's behavior prior to spotting the fish," the study said.

This finding suggests that narwhal hunting near the surface is not without challenges.

Potential play

Intriguingly, the drone footage also revealed the first-ever evidence of narwhals engaging in potentially playful behavior.

In one video, an individual can be seen slowly following a char and gently touching it with its tusk.

"Hits were executed with precision and were not forceful," the study said. "Some involved a brief tap, others a slow push or downward pressure applied to the fish."

During this interaction and others, whales made no attempt to consume the fish, despite coming in close proximity to them.

"At several points the fish just stop and go 'Okay, what's going on here?'" O'Corry-Crowe said.

Scientists asked themselves the same question.

"I think this is a form of play," O'Corry-Crowe said. "It looked like they were exploring a novel kind of stimulus..."

If true, this behavior could change our perception of narwhals.

"If they have time to play, then life isn't constant drudgery all the time," O'Corry-Crowe said. "You think of the Arctic and you think of hanging on by your fingernails, but what if you're supremely adapted to your environment and you have time on your hands?"

Play behavior has been documented in a handful of cetacean creatures and other land animals, such as chimpanzees and elephants.

"It's been rarely recorded and observed, but I suspect it may be more common than we know," O'Corry-Crowe said.

In addition to play and hunting, tusks also appear to have other uses, including serving as a thermometer, capable of not only identifying changes in temperature, but water salinity.

O'Corry-Crowe said that he plans to return to the Arctic to continue studying narwhals, which will likely display more novel behaviors as they grapple with shifting environmental conditions related to climate change.

The other authors of the study were: Maha Ghazal, Mark Gillespie, Paul Galvin, Jason Harasimo, Luke Storrie and Cortney Watt.