by MARY JO DILONARDO –
Known as “the unicorns of the sea,” narwhals are unique for the solitary tusk that protrudes through the tops of their heads. The horn is actually a canine front tooth that can reach as long as nine feet. But until recently scientists weren’t sure what, if any, purpose it had.
Research from 2014 suggests that the tusk is used as a sensory organ, helping the narwhal pick up changes in its environment. Researchers say males of the species may use the horns to look for food or find mates. The results of the study were published in the journal The Anatomical Record.
“People have said it’s everything from an ice pick to an acoustic probe, but this is the first time that someone has discovered sensory function and has the science to show it,” the study’s lead author, Dr. Martin Nweeia from the Harvard School of Dental Medicine, told the BBC.
A team of international investigators worked together to understand the function of the narwhal’s unusual protuberance. To do so, they captured several of the elusive animals and anchored them using a net anchored perpendicular to shore.
The researchers found that the outer cementum layer of the tusk is porous, the inner dentin layer has microscopic tubes that channel toward the middle, and the pulp in the center has nerve endings that connect to the animal’s brain. The structure makes the tusk sensitive to temperature and chemical differences in the environment.
When the tusk was exposed to different levels of salt in the surrounding water, for example, the researchers noticed a change in the narwhal’s heart rate.
The animals can basically “taste” the concentrations of chemicals in the water. Because of that, researchers believe males may use the tusk to find food. They also appear to be able to find females that are ready to mate.
Nweeia told the BBC that he’s fascinated that narwhals put all their energy into growing a single tusk rather than having a set of teeth to help them eat their diet of large fish.
“If you were looking for an ideal and fascinating tooth to study, there’s no question this would be it.”
Footage from Canada may support one of the tentative conclusions Nweeia’s study: using the tusks to find food. One additional quirk? The horns may also help the narwhals prepare to eat that food, too.
The video above, shot using drones by the WWF in Canada in 2017, shows narhwals in Tremblay Sound, Nunavat, striking Artic cod with their tusks to stun them and then gobble up the fish.
Steve Ferguson, of Fisheries and Oceans Canada, explained in a video for the agency that the drone footage shows male narwhals “kind of tracking the cod with the tusk […] and as the cod was positioned close to the tip of the tusk, the narwhal sort of gave it a quick, hard tap that likely stunned the fish — it looked like it was momentarily not moving — and then the narwhal would move in with its mouth and suck in the prey.”
Given that we’re only seeing this behavior now, in no small thanks to the general unobtrusiveness of drones, researchers are eager to learn what other possible uses there are for the tusks. A dual purpose sensory organ and cod stunner is already pretty exciting, so what other uses could these creatures of the deep have for this horn-looking tooth?
Conceptual artist Hannah Rothstein has always been worried about global warming and climate change, but her concerns increased relatively recently.
“With the current political climate it came to a head,” Rothstein say. “I’m worried what the world will look like in 30 years. It’s a one-way street with a lot of issues I care about. If we don’t start making positive changes, we can’t go back.”
Her concern, combined with her love of the outdoors, motivated her to recreate iconic national parks posters, but based on how they would look in 2050 affected by climate change.
The resulting posters make you do a double take, as they are familiar yet not. Waters have receded, trees are dead, and animals are missing.
Rothstein researched how each of the seven parks she re-designed would be impacted by climate change by studying each park’s official website, reading news articles and digging into scientific studies.
“Doing this research I was so scared. It was a powerful motivator,” she says. “I’m scared about what could happen and will happen very soon. We don’t know how our water will be or our air will be or if pine trees (in the Southwest) will exist. It’s all coming very soon.”
Much of what she found surprised her, but most shocking personally was the pine beetle infestation in her home park of Yosemite.
“I went to Yosemite in March for a friend’s birthday and saw about 30 percent of the trees were brown. Before, maybe, I thought they died because they were just old. Now I know it’s probably because of the infestation.”
For each poster, she lists the potential realities of climate change versus the amazing wonders. It’s “scarce drinking water” and “dying mangroves” in Everglades National Park and “species die-off” and “wildfires” in Great Smoky Mountains National Park.
Because people often think that climate change won’t have an impact in their lifetime, Rothstein chose 2050 as her timeline in hopes of changing that perception.
“I wanted the effect of climate change to be very real,” she says. “Sometimes we talk about it in such an abstract way and I wanted to show how close it is.”
Rothstein says she grew up going to national parks and loves going to them now. She goes to Yosemite most often, but travels to the parks throughout California and the Southwest and is heading to Glacier National Park in Montana this summer.
“They are special places to me and it’s my religion, really, going out into nature,” she says. “The vast wilderness we have here is something special.”
Rothstein is selling limited-edition prints and donating a portion of proceeds to climate-focused organizations including the National Resources Defense Council and the National Parks Conservation Association. She’s hoping to get her work into natural history museums and nature centers and is turning them into paintings.
“The response has been phenomenal. I’ve been excited to see how meaningful it has been to people. Generally sadness is the most overwhelming emotion, but I also hope they are inspired to change,” she says.
“Obviously these images are very sad and I’m aware of that, but I want people to remember that it is possible to create the positive change we need. We need to find the energy and gusto to fight, because it is possible. But we need to start acting now.”