Top Ten Sharks #2 – The Greenland Shark, Somniosus microcephalus

The Greenland Shark – Many of them have had their eyes so parasitised by a specific copepod parasite that they are effectively blind, relying on their other, very acute, senses to help them find prey. (Credit: Hemming1952 CC-BY-SA 4.0)

Ooh it’s that time again where I get to enjoy words. ‘Greenland Shark’ is a bit dull, invoking images of Greenland, and sharks.

But let’s get a bit deeper on that binomial! Somniosus microcephalus. Somnus, in Roman mythology is effectively the Godly incarnation of sleep. The roots of words like ‘insomnia’ or being unable to sleep. In this case ‘somniosus’ means sleepy shark. Micro, as in small, and we’ve dealt with ‘cephalo-‘ with the hammerheads the head of which is properly named a ‘cephalofoil’ or headwing. So ‘cephalo-‘ means ‘head’ or ‘of the head’.

So put it all together and the Latin name for this thing is ‘small headed sleepy shark’. Oh my God I love it already.

It’s actually a member of the family Somniosidae – The ‘sleeper sharks’ and they are named that for the reason you think. They are all notoriously slow sharks, thought to be of little danger for people, a little lethargic and laid back. Like reggae shark.

For anyone who looks at some of these Latin binomials for animals and wonders what they mean, most of the time this is the kind of silly shit it translates to! Don’t be intimidated, it’s the fanciest cover-up for nonsense you can imagine.

So what makes the Greenland shark so special for it to be our number two? Is its head actually that small?

Well no, they’re actually a sizeable shark. Average total length of observed specimens would probably be around 4-5m (around 12-14 feet) but it is believed that they can reach lengths of around 7.3m – effectively putting it on par for length with the white shark.

Approximate scale of a Greenland shark to a human diver. (Credit:
marine animal infographics CC-BY-SA 4.0)

It is less solidly built than the great white, though, a lot more slender and less mass. The tiny head part I suspect comes from the fact that it is quite a slender species that tapers to a pointy head, giving it a small-headed sort of appearance.

One of the coolest things about the Greenland shark is you can become intoxicated from eating its flesh. Which is actually eaten (after preparation to decrease toxicity) in Iceland as a delicacy. The shark’s flesh has a high concentration of the chemical trimethylamine N-Oxide, no it’s not one of the ingredients used in Heisenberg’s special blue meth, that would be standard methylamine.

In the Greenland shark it is multipurpose. For one it helps keep their bodies stable at high pressures such as in the deep oceans where the Greenland shark has a habit of going. It also acts as a stabiliser for proteins in the presence of something else the Greenland shark’s body and flesh is high in, urea. Yes, the stuff what we piss a lot of out. Well in the sharks, along with the trimethylamine, they maintain high concentrations of urea to aid buoyancy and body stability at pressure.

That’s a lot of biochemistry – what does it mean? In order to stop it turning into a pancake under the weight of all the water it swims in the Greenland shark is full of piss and a chemical that can make you act really, ridiculously drunk if you ingest too much of it.

The Greenland shark is quite rare, so expect to see a lot of the same photos you’d get on wikipedia because I can’t afford to pay for license fees! (credit: Justin CC-BY-2.0)

When Icelanders prepare Greenland shark meat for eating it usually involves a process of fermentation and air-drying to remove the worst of these compounds. It probably tastes revolting, I don’t know for sure but I’ve never known anyone (outside of these nations who has acquired the taste for it) to ever say any of these fermented shark products is good.

Is that it, though? The Greenland shark makes it to number two on the list because it’s full of piss?

Nuh-uh! That was just one biochemically interesting thing about the Greenland shark.

The other biochemically interesting thing is where it lives. Cold water! What does cold do? It slows stuff down. Like metabolic processes and shit. Unless you’re an ‘endotherm’ – that is you produce your own warmth or are, ‘warm-blooded’ which Greenland sharks are not.

So a study of Greenland sharks discovered they are, as far as we know, the longest living vertebrate species on planet earth. Why? We’re not entirely sure but the thinking is because cold makes everything go slower; metabolism, growth, sexual maturity, gestation of infants and aging. The average lifespan of the sharks surveyed was 272. Sexual maturity does not occur in the Greenland shark until around 100-200 years old, and the oldest observed specimen was somewhere in the region of 300-500 years old. That shark, studied around 2015-2016, would have been born sometime between 1504 and 1744 based upon their carbon-dating methods.

The known distribution range of the Greenland shark. As you can see, it mainly sticks to the frigid waters of the North and the Arctic circle, but it has been found as far south as Portugal. It has been suggested its range could extend beyond what we currently known, but so deep we rarely encounter it. (Credit: Chris_huh CC-BY-SA 3.0)

Their gestation period is more of a gestation generation. It takes an estimated 8-18 years to gestate a litter of Greenland shark pups. They are another ovoviviparous species, so they lay eggs within themselves and hatch them inside them before giving birth.

These numbers are unbelievable, though. Imagine if you weren’t mature enough to fuck until you were 150! And it took you 15 years to carry a child to birth! The numbers are only somewhere in the region of 5-8 times the average human lifetime yet they put our oh-so-brief sojourns with consciousness in perspective. In evolutionary time 500 years is not so much, but to us it’s forever. That oldest shark they fished up may have been born a full 80 years before William Shakespeare, he was born in 1585! That shark may have lived a full human lifetime of its own, before William Shakespeare was born!

So clearly this super slow freak shark eats…I don’t know…ice or frozen shrimp or something? Right, how can something so old and sluggish possibly hunt?

You’d be surprised.

A gif of this…potentially not-so-gentle-giant. Although I don’t think they have been known to attack humans I wouldn’t mess with anything that eats polar bears. (Credit: Blue World via LannaIyuki – MakeaGif)

We’re not entirely sure, it’s very hard to see Greenland sharks in the wild given that the only places they get close to the surface are ridiculously cold waters, but they are still an apex predator and quite opportunistic too, by all accounts. Smaller sharks, skate, eel, herring – standard predatory fish shit is common prey. The smaller ones eat a lot of squid, a lot of sharks like eating squid, I like eating squid. Squid’s good. But then they get weird.

Now there is a theory that Greenland sharks are a bit of a stealthy hunter, they are after all a muddy-sea-grey colour, very slow, very sedentary and yet large sharks are often found with seals in their guts. Around Svalbard it seems to be a common feature in their diet.

And moose.

And a whole reindeer.

And polar bear.

No I’m not kidding. Again, Icelanders regularly fish these things up, they get picked up as bycatch for many other Northern sea fishers, we’ve cut open numerous sharks, we’ve seen their stomach contents.

This shark looks like it has ridiculously blue eyes! (Credit: Justin CC-BY-2.0)

Chances are a lot of this stuff is scavenged. Great white sharks are remarkable hunters and even they are carrion feeders, when the water you’re in is close to 0°C, you can’t be bothered to move it’s so cold and you find a dead moose floating in the water near you? Well you don’t look that gift moose in the mouth, you put it in your own!

If you’re asking whether it’s more likely a shark snuck up on a polar bear and ate it or a polar bear, either weakened or dead from swimming long distances between sea ice, was opportunistically eaten by a Greenland shark, the latter seems more likely. But still, you’d think this thing would be dull, it’s slow as hell and lives in a natural refrigerator and meanwhile Greenland shark is like “Whole reindeer? Anyone fancy eating a whole reindeer, I could really go for a reindeer right about now!” They are incredibly well adapted creatures.

Well, except to us. Classed as vulnerable and, with their low reproductive rate, high time investment in their own lives, human commercial fishing impact on Greenland shark is a huge danger. Whether it’s deliberate fishing or as bycatch it doesn’t matter, every adult shark dead is a shark it takes 150 years to replace.

Climate change is also likely to massively impact both water temperatures and competition up in the arctic seas. If the water up there warms, more prey will no doubt arrive but so will more competition. Those numbers will also drive fishing to those areas, increasing the risk to the Greenland shark from fishing yet again.

This Greenland shark was filmed in the St. Lawrence Estuary, Quebec, Canada – showing these amazing sharks can live in brackish waters, too. (Credit: LannaIyuki – MakeaGif)

It’s a case where you really have to look at those numbers again. It takes approximately ten times as long for a Greenland shark to reach sexual maturity as it does a human being. If we take a generation as being approximately 25 years, humans could give birth to, raise and feed Greenland shark to 6 generations before one shark born the same day as the first human could reach maturity.

We really need to put that into perspective. I adore this species because it is one of few species on the planet that can make us do that. As an animal representative of the longevity club it feels more real to us than the seeming immortality of hydra species, the clone-related longevity of some fungi and grass making them technically tens of thousands of years old, or even the relatively available ages of trees in the thousands of years.

The token parasitic copepod on the eye. Almost all individuals caught or document have this parasite and it is believed to severely impair their vision, by both getting in the way but also damaging the cornea. Their relative success regardless would suggest they rely less on their vision than other sharks (Credit: The Physiological Society – Used without permission)

It’s different when it’s got eyes, and teeth, and internal organs. It’s different when it’s a creature with blood pumping through its veins. It’s so much like us and yet can you imagine what you’d do if your average life span was 300 years?

When thinking about the conservation of the Greenland shark those are the scales we have to think in, and it’s not easy for us to do so. I would love to be an old man today, talking about how I went to see Shakespeare and the Lord Chamberlain’s Men performing at the globe. I’d love to give contemporary opinions on what happened during the reformation, the flip-flopping of persecutions between Catholics and Protestants that followed. I would love to have first-hand accounts of the English civil war, and the puritanical Cromwell years. I’d love to have seen the industrial revolution blossom into the age of industrial titans, of concrete and steel until that technology slowly shrank down and shrank down and we had computers more powerful than the ones which took up a whole room and put men on the moon in our front pockets. I can’t, because I’m not a Greenland shark.

But they are. Animals that have lived through all those events are, they exist. That is special. Truly special and worthy of our respect and protection.

Want to dive deeper into some aquatic shark content?
Our Introduction will give you the basics of shark biology, ecology and natural history.
#10 – The massive, magnificent megalodon – a prehistoric giant!
#9 – The beautiful and quick blue shark
#8 – Known for it’s spiral of jagged teeth, Helicoprion – the Buzzsaw shark!
#7 – The frilled shark, a mysterious living fossil with much to tell us about sharks past.
#6 – The Great White, Apex predator, whale scavenger, more intelligent than we thought.
#5 – The Megamouth Shark – One that tells us more about what we don’t know!
#4 – The Graceful Hammerhead family – Much overfished, and is one a veggie?
#3 – The aparently philosophical basking shark! – Happy just existing.

#1 – The Whale Shark, a titan of the seas, a gentle giant and the perfect shark.

Published by Karl Anthony Mercer

Karl Anthony Mercer is a writer, poet, author, musician and part-time dandy. He can often be found squatting in fields looking at insects (he is an unapologetic wasp fanatic), wandering around museums over-dressed, or hiding in a dank corner singing sad songs on a small guitar. His writing on WordPress consists of MercersPoems - an outlet for his poetry often using natural imagery, gothicism and decadence to explore the struggles of living as an autistic person; and We Lack Discipline - Where he writes about factual, often academic topics he has learned and is interested in (e.g. biology, psychology, Roman history etc.) with an inimitable, often light-hearted and irreverant style. You can support Karl by; Subscribing to the We Lack Discipline Patreon - Or buying him a coffee (he loves coffee!) -

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