Researchers in Canada have captured remarkable drone footage of narwhals that may solve a longstanding mystery surrounding the unique sea creatures.

For centuries, scientists have offered competing theories for the purpose of the prodigious tusk possessed by the marine mammals.

Some have suggested that it used as a weapon, while others argue that it could be utilized for echolocation.

Now thanks to rare footage of narwhals in their natural habitat, it appears that researchers may have an answer.

In the video, the creatures can be seen swimming through the water and occasionally striking smaller fish with their tusk in a rapid fashion that scientists say renders the prey stunned and thus easily eaten.

The footage constitutes the first time this behavior seen being exhibited from narwhals and indicates, at the very least, that their tusks are used to harvest food.

That said, researchers say that the findings may be the proverbial tip of the iceberg when it comes to ways in which the narwhal uses its tusk, since the appendage is covered in nerve endings which, no doubt, provide the creature with a wealth of insight into its surroundings.