Between 1993 and 2001, a horror story  unfolded off the coast of Nova Scotia.

During those eight years, the corpses of  almost 5,000 seals washed up on Sable Island. Most had gruesome injuries, like they'd  been run through a spiralizer.

What was it, lurking offshore,  peeling seals like giant oranges? These bizarre deaths had to  be the work of something big,   and suspicions turned to a  mysterious beast from the north: an enigmatic shark. It lived in both the darkest ocean  depths and under the Arctic ice,   blindly searching for its next victim at  a deathly slow, but unrelenting, pace.

But, it turns out, it was being framed… by us, and our expectations about sharks, when  the actual culprit may have been other seals. While this strange shark is a predator, and  does eat some things we wouldn’t expect,   its real weirdness lies in its ability to  outlive every other vertebrate on the planet. [♪♪ INTRO ♪♪] The Bizarre Beasts pin club is open  for subscriptions for the whole month! Sign up by October 20th and your  first pin will be a spooky shark.

The Greenland shark, Somniosus microcephalus,  can be found slowly puttering around the chilly   waters of the North Atlantic,  mostly by continental shelves. This species is very tolerant  of the cold and the dark: it survives Arctic temperatures all year long,   and at least one individual has  been seen as deep as 2,200 meters. In fact, their seasonal behavior gives the   impression that they maybe  prefer these conditions: they keep to the depths during the summer,  and only come up to the surface in the winter.

Greenland sharks are part of the  family of “sleeper sharks,” whose name refers to how much of a hurry they are not in. The species’ scientific name literally  translates to “sleepy, small head.” And the slowness kind of makes sense when  you imagine being that cold all the time,   but these sharks are also predators, which  means they have to actually catch prey. So how does that work?

Well, the Greenland shark’s diet consists of  whatever it can get its jaws on, from fish,   to various invertebrates, to  even some marine mammals – but how they manage to eat some of  their prey has been kind of a mystery. Especially seals. Like, how does this slow guy catch up to a seal?

The answer might be that they don’t. Seals sometimes sleep underwater to  avoid polar bears and a sleeping seal   is much less likely to outswim a Greenland shark. These sharks also have one particular  oddity that might provide a hunting assist: they are pretty much all parasitized by a  small copepod that lives on their eyeballs.

They don’t seem to rely much  on their vision for hunting,   so apparently that does not affect their daily lives. But it has been theorized that these  dangly little crustaceans might actually   act as lures that attract some of  the shark’s potential prey items. That said, there hasn’t been any  direct evidence to support this,   so maybe that doesn’t solve  the problem of speedier prey.

But Greenland sharks definitely scavenge a lot of dead stuff, which doesn’t swim away nearly as fast as the living things! Scavenging could also explain, for example,  the polar bear bits that have been found in   their stomachs, not to mention all  the moose, reindeer, and horses… But more recent accounts suggest that these sharks   might actually be capable of sudden  bursts of speed, crocodile-style. So it’s not impossible that they  could be snagging some of their   larger mammal prey right off the water’s edge.

As for what eats them, it doesn’t seem  like Greenland sharks have much to fear. They’re big, typically between 3.5 and 5 meters, so not a lot of other local species are likely to bother them. There is some circumstantial evidence that sperm  whales may occasionally scarf down a shark or two,   but this also might have been  a totally isolated incident.

And they’re potentially toxic to  mammals unless dried or fermented,   so they’re probably not a super routine food  item for anyone but humans and their sled dogs. The reason for their toxicity, though,   is that the compounds found in their  blood act as a natural antifreeze, which is crucial for their polar home. And being generally unbothered by  predators allows Greenland sharks   to do the opposite of ‘live fast and die  young’ from an evolutionary perspective, it gives them a lot of time to reproduce.

We don’t know for sure how long it takes,   but one estimate puts their gestation  time at somewhere between 8 and 18 years. And the species is ovoviviparous,   meaning that they give birth to live  pups after the eggs hatch inside of them. For a while, scientists believed that  Greenland sharks typically gave birth   to 10 pups at a time, each somewhere  between 40 and 100 centimeters long.

But a 2020 study found that they potentially  produce over 200 pups in one go, and maybe even 300 plus, each closer to the 40-centimeter  end of the birth size range. Producing so many offspring makes  a lot more sense once you realize how   long it takes for one of these sharks to be  old enough to reproduce in the first place. Even just reaching their adult  size is quite an accomplishment,   because they grow even more slowly than they move: only about 1 centimeter per year.

So some quick math tells us that… yeah these sharks live a long time. The Greenland shark’s lifespan is, as  far as we know, something like 400 years,   making them the longest-lived  vertebrate species on the planet. Females don’t even reach sexual maturity  until they are at least 130 years old, and we have no idea how long it takes for males.

So a young mother shark who just had her  first litter this year could have been   alive to ride the original Ferris wheel when  it was unveiled at the Chicago World’s Fair! Barring one or two logistical issues... like, being a shark. And there are almost certainly sharks  swimming under the ice right now who… are older than the Taj Mahal… could have been present for nearly every  attempt at finding the Northwest Passage… pre-date Newton’s Theory of Gravity… lived through, but did not benefit  from, the invention of the piano, and… failed to protect Galileo  from the Roman Inquisition.

Point is, it’s a pretty big deal  for a vertebrate to live that long. But since nobody has been able to keep  super close track of the exact same   sharks for all this time, how do we  actually know how long they can live? Did someone strap a stopwatch to a shark a  century or so before stopwatches were invented?

Do we just cut them open and count the rings??? Okay, actually we do count the  rings in the vertebrae of most   sharks to estimate their age, so that might be a bad example. But for Greenland sharks, instead,  we radiocarbon date their eye lenses!

Their cartilage is even softer  than in other shark species,   so they don’t get the backbone growth rings  that would traditionally help tell their age. Luckily for us, vertebrates have proteins  in the center of the lenses of their   eye that form while they’re gestating and  don’t change for the rest of their lives. So that’s where carbon dating comes in.

Carbon-14 is a naturally  occurring isotope of carbon,   which prefers to have a stable atomic mass of 12. Because it’s radioactive, it  decays at a very predictable rate. Living things constantly exchange  carbon with their environment for   their whole lives, but stop as soon as they die.

This means that there’s a specific ratio of the  carbon isotopes in their bodies at any given time,   which we can compare to the known ratio of  carbon-12 to carbon-14 in the environment. But once they’re dead, whatever carbon-14 was in  their tissue starts to decay back into carbon-12. And by comparing the ratio of  carbon-12 with the remaining carbon-14,   we can use that isotope’s decay rate to  extrapolate an estimate of when they died.

Nuclear testing in the 1950s  and 1960s almost doubled the   amount of carbon-14 in the atmosphere,  though, which means that we also now   have a very specifically measurable “bomb  pulse” in the graph of carbon isotopes. And wouldn’t you know it, all kinds of living   things now have carbon isotope ratios  consistent with this bomb pulse, too. With all that in mind, a team of scientists  used this spike to very precisely date some   smaller Greenland sharks back to the early  1960s, and then used this knowledge along   with the sharks’ sizes to calibrate a more  exact growth rate throughout their lives.

When all was said and done, they  concluded that the species can, for sure,   live at least 272 years, with  their largest specimen coming   in around possibly 392 years,  give or take a century or so. All right, so how we measure  their age is one thing,   but how do the sharks live so long to begin with? Well, a lot of it may be due to a slow metabolism.

Being slow to grow, for example, has been  correlated with longer lifespans in a number   of other ectothermic, or cold-blooded, species. But even simply being colder seems to  extend some of these animals’ lives,   apparently just by slowing them down. Living fast causes damage to cells  and DNA in a way that ages them, and ages the animal, sooner than you would see in a slower life history.

And being cold and slow is the  Greenland shark’s whole vibe! Their sluggish metabolism seems  to be not just a consequence of,   but actually an adaptation  for their hostile environment. Burning up as little energy as possible  allows them to survive between scarce   meals much more easily than, say,  their seal and whale neighbors.

This also means that their environment can sustain   higher shark populations even  with such limited resources. And sure, this ability to survive  starvation helps them to, you know,   not die, but it also has the side effect  of extending their lifespan like crazy. At least one research team  is convinced that this means   a life expectancy of 400 years is too  short of an estimate for these sharks.

It’s just like with the naked mole-rat:  evolving to survive really specific,   harsh conditions can just  accidentally make you live forever. And for good measure, a 2026  study of the Greenland shark’s   genome reveals some of longevity’s greatest hits,   like disease and cancer resistance genes,  and extra fancy DNA repair mechanisms. However, this work was published literally  one week before we wrote this episode,   so expect even more cool discoveries to follow.

So what exactly is the lesson from this big old shark? Emphasis on both big and old? Certainly humans are always interested in  understanding how other species live for a   long time, because we get pretty obsessed  with trying to extend our own lives.

But there are a couple of important ways, and reasons, to de-center ourselves in this shark conversation. For one thing, the knowledge that some of these  beasts have been plodding around under the ice   since before the telescope was invented  should give us some major perspective. But also, more and more fishing activity by humans   in the Greenland shark’s habitat means  a growing risk of death by bycatch.

And because the time scale that this  species lives on is so much longer than   we humans can really grasp, there are some  very important conservation considerations   when it comes to how easily they  can replenish their populations. So in many ways, we have a lot  to learn from our shark elders. Sign up for the pin club at BizarreBeastsShow.com  and help us keep this channel going.

If you want this shark to be your  first pin, sign up by October 20th. Thank you for watching Bizarre Beasts! You help our non-profit bring more educational  videos to more people every time you watch,   comment, share, and tell people about a  Bizarre Beasts video and the pin club.

And speaking of pins, we're having a sale. Do you need more fish pins in your life? Well, right now at BizarreBeastsShow.com all  our past pins are buy three, get one free!

That means you could join the pin club  to get the incredible new Greenland Shark pin,   and then stock up on other weird pins from the past like the Port Jackson Shark,   and the bonnethead shark, and a whole school of European anchovies, and then you can get this incredible gar pin for free! Or heck, we have all types of weirdos! Maybe you need this beautiful tridops pin,  and the Aldabra rail, and a caecilian, one of my favorites, and then you get this  raven and desert tortoise pin FOR FREE!

That’s two critters in one pin! All the al la carte pins are all  left over from the pin club,   so we will not be reordering them if  they run out, and they may run out! Also, if you want a real weird guy, I  hear we are almost out of these Hank pins… Show your support for the show and  Bizarre Beasts everywhere   and pick up some pins right now at BizarreBeastsShow.com And now, for some bonus facts… [♪♪ BONUS FACTS ♪♪] Time and disease and eyeball  crustaceans do not stop this beast,   so getting caught in fishing nets  might be their only real threat.

But what about that “being hunted by a  sperm whale” story we mentioned earlier? It really comes down to a series of clues  that could point to at least one specific   whale maybe eating a bunch of Greenland  sharks, but we may never know for sure. It all begins with a guy mentioning a recording of   a shark seeming to flee from the sound  of a sperm whale’s echolocation clicks.

Not exactly a smoking gun.

Also: it’s kind of hard to imagine  a Greenland shark going anywhere   with any sense of urgency, but  that’s neither here nor there. Curiously enough, though, orcas in the Pacific  are known to chow down on the closely related   Pacific sleeper shark, which, like its  polar cousin, has ridiculously rough skin. The orcas’ teeth were consequently  all ground down to nubs. And the terrifying clicking sperm  whale of that one shark’s nightmares?

Well when it died, its teeth  were also worn down. This could have been from a lifetime  of chomping on Greenland sharks,   or it could have been from any  number of other possible causes. We cannot know for sure.

Some things about the Greenland shark, and its potential predators, will just have to remain a mystery for now. [♪♪ OUTRO ♪♪]