May 15, 2017

(Video) Scientists crack mystery of how Narwhals use their tusks

Narwhals are superb creatures - they have a great name and a striking appearance, largely due to the long and imposing tusks protruding from their heads.

But as remarkable as these whales' tusks look, it has until recently been unknown exactly how they are used.

Drone footage shot around the remote Nunavut region of Canada has put an end to the mystery, revealing that the so called "unicorns of the sea" use their tusks to stun prey.

In behavior caught on camera for the first time, narwhals are seen using the tusks as a club to hit and stun Arctic cod. Once stunned, the fish are easier to catch and eat.

Adam Ravetch of the World Wildlife Fund Canada, and researchers from Fisheries and Oceans Canada, were working in the far Northeastern region when they got the footage.

The remoteness of locations in which narwhals are found goes a long way to explaining why the behavior has not been noted before.

Three quarters of the world's population can be found in the Lancaster Sound, close (in relative terms) to where to footage was taken.

The tusks are likely multipurpose

Marianne Marcoux, a research scientist for Fisheries and Oceans Canada, said that: "Drones are very exciting, we can see things we couldn't see before."

The bigger planes previously used for such ventures often came up with incomplete footage or scared the narwhals.

"They don't jump like other whales. They are also notoriously skittish. This is an entirely new observation of how the tusk is used," said Brandon Laforest, a senior specialist of Arctic species and ecosystems with WWF-Canada.

However, there may be other uses for the tusks, along with that seen in the new observation. Using them as ice picks, weapons, for echolocation or for sexual selection are all possibilities.

Laforest suggests that, given the thousands of nerve endings and pores covering the tusks, they may be important as sensory organs.

"They can feel their surroundings similar to how a human's broken tooth would have feeling," explained Marcoux.

The tusks are indeed a canine tooth on the heads of males, sometimes growing up to 9 feet long. All of their tooth-growing ability seemingly having gone into this impressive body part, they have no internal teeth and swallow food whole with a sucking action.

Protecting the narwhal population

Along with solving the mystery of the tusks, at least partly, the work done by the researchers in the region will help with vital conservation work.

Experts had thought that narwhals only feed in their winter waters around the southern part of Baffin Island, but the latest research shows they also feed in their summer waters.

Mineral extraction, tourism and climate change (their food web is entirely dependent upon sea ice), all threaten the narwhal population, 90 percent of which is in Canadian waters.

They are under threat from colliding with ships and from having their communication abilities disrupted by underwater noise from vessels.

The northern Inuit community is also heavily reliant upon narwhals for food and crafts.

The Canadian government is currently considering making the Lancaster Sound a protected area. Tailoring shipping to cause lease disturbance, and assessing narwhals calving areas, are important next steps in conserving the splendid whales.


Image credit: Glenn Williams/NIST