The Narwal's Signature Tusk May Be Multipurpose

What is the point of a narwhal's signature tusk, which is actually just one, long spiraled tooth? The answer may be multifaceted, according to new research. Prior research indicates the lengthy tooth, rarely seen in females, is a sexual display, used to communicate a male's fertility—the larger the tusk, the larger the testes—and to establish dominance. The tusk, which has nerve endings that detect changes in the water around the animal, may also be used as a weapon, both in mating battles and in the hunt for fish, per the Washington Post. A new study describes how the tusk may have a use in foraging, but it also notes the tusk's use in what "may be the first recorded evidence of play" in narwhals.

While using drones to film whales in the Canadian Arctic in the summer of 2022, researchers observed narwhals "using their tusks to hit, manipulate and influence the behavior of fish," according to the study published Feb. 27 in Frontiers in Marine Science. They may be able to "deliver sufficient force with their tusks to stun and possibly kill fish," the study notes. But it also describes evidence of "exploratory-object play" in footage of three narwhals chasing a single fish they didn't look particularly eager to catch. Indeed, there appeared to be no intent to harm, kill, or consume the Arctic char even as a narwhal's tusk came into contact with it. The narwhals appeared to be keeping pace with the fish but eventually let it swim away.

It was "like a cat-and-mouse game," says study co-author Greg O'Corry-Crowe, a biologist at Florida Atlantic University's Harbor Branch Oceanographic Institute. Researchers note the behavior was filmed as narwhals slowly moved around a bay, interacting with other whales but largely avoiding foraging and mating. In other words, a good time for play. O'Corry-Crowe remains confident the tusk's primary use is in mating, but he says it likely has other uses humans are only beginning to understand. "The dexterity and use of the tusk was what was really striking," he tells NPR. "It's like they're not wielding a broadsword, they're using a very precise surgical instrument." (More discoveries stories.)