When Narwhals Encounter Humans, Terror Pushes Them to the Limit
A new study finds that narwhals race dive deep with their hearts barely beating as they escape humans.
When a deer freezes in your car’s headlights it’s because the pupils of their eyes are wide-open from being in the dark and they don’t know what to do but wait until they adjust. Presumably this is a similar phenomenon in rabbits — a terrified state referred to in Watership Down as going tharn. But what narwhals do when scared by humans combines going tharn with the opposite — flight — as they dive deep into the sea at top speed, frozen still except for the tails propelling them downward and away.
A study just published in Science documents this strange response to the terror that is humanity. What’s weird is that, as narwhals’ tails paddle at up to a brisk 25 strokes per minute, their heartbeat drops all the way down into extreme bradycardia and a barely-there three beats per minute. Their normal resting heart rate is 60 beats per minute, and it’s about 20 during regular dives, which allows them to conserve precious oxygen underwater. In fright, they also dive repeatedly to depths of 45 to 473 meters according to the new research.
As one of the researchers, biologist Terrie M. Williams, tells Science, “That was astounding to us because there are other marine mammals that can have heart rates that low but not typically for that long a period of time, and especially not while they’re swimming as hard as they can.” Narwhals have been observed in this fast-moving cardiac stasis for as long as 10 minutes.
Narwhals respond only to humans in this way. With predators such as Orcas, they slide quietly under ice or gather in waters too shallow for the killer whales to follow. But with humans, it’s something else, and with climate change causing ice to melt, Monodon monoceros are likely to be in more frequent contact with us. Their reaction is so extreme that, “There is a concern from our group that this is just pushing the biology of these animals beyond what they can do,” says Williams.
For the study, Williams and her team worked with indigenous hunters from Greenland. Narwhals were trapped in nets and then released after submersible electrocardiographs, depth, and acceleration recorders were attached to them with suction cups.
Placement of monitoring devices (T.M. WILLIAMS ET AL/SCIENCE 2017)
The narwhals’ frantic response to people has to be awfully hard on them. The study estimates that they burn three times the energy they consume at rest, and that fleeing with what the report terms “cardiac freeze” tears through the available oxygen in their lungs, blood, and muscles, quickly exhausting up 97% of it.
Narwhals’ energy consumption during the initial escape dive and the period afterward is incredible — they get to depths of 45 to 473 meters — and alarming (T.M. WILLIAMS ET AL/SCIENCE 2017)
While understanding narwhals’ response to human interaction — and reducing those intrusions — may be important to their survival as a species, hopefully further catch-and-release research will unnecessary, given its cost to the subject narwhals. Still, the scientists remain curious to know if other human activities, including seismic exploration, noise, and hunting, produce the same or a similar reaction. Let’s hope not.
Sharon Salzberg, world-renowned mindfulness leader, teaches meditation at Big Think Edge.
- Try meditation for the first time with this guided lesson or, if you already practice, enjoy being guided by a world-renowned meditation expert.
- Sharon Salzberg teaches mindfulness meditation for Big Think Edge.
- Subscribe to Big Think Edge before we launch on March 30 to get 20% off monthly and annual memberships.
The 21st century is experiencing an Asianization of politics, business, and culture.
- Our theories about the world, even about history or the geopolitics of the present, tend to be shaped by Anglo perspectives of the Western industrial democracies, particularly those in the United States and the United Kingdom.
- The West, however, is not united. Canada, for instance, acts in many ways that are not in line with American or British policies, particularly in regard to populism. Even if it were united, though, it would not represent most of the world's population.
- European ideas, such as parliamentary democracy and civil service, spread across the world in the 19th century. In the 20th century, American values such as entrepreneurialism went global. In the 21st century, however, what we're seeing now is an Asianization — an Asian confidence that they can determine their own political systems, their own models, and adapt to their own circumstances.
They didn't know it, but the rituals of Iron Age Scandinavians turned their iron into steel.
- Iron Age Scandinavians only had access to poor quality iron, which put them at a tactical disadvantage against their neighbors.
- To strengthen their swords, smiths used the bones of their dead ancestors and animals, hoping to transfer the spirit into their blades.
- They couldn't have known that in so doing, they actually were forging a rudimentary form of steel.
Can sensitive coral reefs survive another human generation?
- Coral reefs may not be able to survive another human decade because of the environmental stress we have placed on them, says author David Wallace-Wells. He posits that without meaningful changes to policies, the trend of them dying out, even in light of recent advances, will continue.
- The World Wildlife Fund says that 60 percent of all vertebrate mammals have died since just 1970. On top of this, recent studies suggest that insect populations may have fallen by as much as 75 percent over the last few decades.
- If it were not for our oceans, the planet would probably be already several degrees warmer than it is today due to the emissions we've expelled into the atmosphere.
SMARTER FASTER trademarks owned by The Big Think, Inc. All rights reserved.