For an animal with an ivory appendage half the length of its body protruding from the top of its head, a narwhal moves in the water with surprising grace.

“It’s almost mesmerizing,” said Greg O’Corry-Crowe, a research professor at Florida Atlantic University who studies marine mammals. “The precision with which they wielded their tusks, it wasn’t like a broadsword. It was like a surgical instrument or the bow of a violin.”

In research published last month in the journal Frontiers in Marine Science, Dr. O’Corry-Crowe and colleagues make the case that narwhals aren’t only showing off with their tusks — the appendages have a variety of demonstrated uses that help the animals survive in the ocean.

The narwhal’s tusk was an inspiration for unicorn myths. It’s known that only males have them, with rare exception, and that a big tusk is something female narwhals look for in a mate. But the animals have been difficult to study.

“They’re extremely shy and elusive whales,” said Kristin Laidre, an applied animal ecology professor at the University of Washington who was not involved in the study. “They’re really hard to approach. They’re really skittish.” She added that narwhals tended to spend their time far from shore and diving deep into the water, and that doing research in the Arctic was logistically complex, making them a challenging species to observe in the wild.

With the help of local Inuit communities, the team of researchers identified a spot in the Canadian High Arctic to set up camp and fly drones. The calm waters of Creswell Bay in Nunavut, where narwhals had previously been observed spending their summers, were shallow and clear and — combined with the 24-hour daylight in August — allowed the researchers to film some of the best footage of narwhals ever captured.

As Dr. O’Corry-Crowe and team studied their recordings, they identified previously unobserved tusk behaviors. And one of those behaviors looked an awful lot like playing.

In more than one instance, narwhals chased arctic char but did not, strangely, try to catch and eat it. The whales even slowed down when necessary to keep the fish just off the tip of their tusks. When they did interact with the fish in these encounters, they used gentle taps or nudges — a stark difference more aggressive uses of their tusks when they were observed hunting fish. And in fact, the arctic char also didn’t seem to always be trying to escape the pursuing narwhals.

“They are not actually foraging on the fish, and we were hesitant to use the word ‘play,’ but that is really what it looked like,” said Cortney Watt, a researcher with Fisheries and Oceans Canada, and an author of the study.

She added that it was also possible the older narwhals were using such behavior to teach younger ones how to pursue prey.

The footage also captured the whales doing some deft spearfishing. While narwhals had been seen before using their tusks to stun fish before eating them, this is the first published study documenting that behavior. The narwhals stabbed and slashed fish with both the tip and the shaft of their tusks, disabling and possibly killing the fish before consuming their prey.

While spearfishing, the narwhals were also interrupted by glaucous gulls, which kept diving into the water to snatch the fish. Though sea gulls are known to track and scavenge off the hunts of other sea mammals, this was the first recorded interaction of this behavior with narwhals, specifically.

Dr. Laidre said that it was best not to jump to too many conclusions about narwhal behavior observed in a single study. The researchers agree, and that is why they didn’t want to label the narwhals’ interactions with arctic char as play explicitly. Dr. O’Corry-Crowe added that many of the behaviors his team observed “raise more questions than they answer, but that’s what’s so exciting.”

“What we really need to do is go back and do some more work,” he said. “And I can’t wait to do that.”