Why Antarctic Oceans Turn Animals Into Giants

 Let’s imagine you’re lost in the Antarctic Ocean, and you make the mistake of looking down into the water below you.  You might think all you’d see are tiny fish or clouds of microscopic plankton,  but what you actually find is much more terrifying.  Spiders with leg spans longer than dogs are crawling around on the seafloor,  jellyfish with tentacles longer than whales are slowly drifting by,  and even the most normal-looking fish are now just abnormally gigantic.

 And yes, these guys are all real, as the freezing cold environment here has let evolution just go completely off the rails.  This is the world of polar gigantism, a phenomenon that most people are totally unaware of,  because it only happens in the coldest oceans on Earth.  And you’d think in a place where everything’s freezing and there’s barely any food to survive,  that most animals would get smaller and smaller to conserve energy.

 But the complete opposite happens.  All animals in this region turn into a sort of super-sized variant of themselves,  making small things big and big things huge.  So why is this effect even happening in the first place?  To understand polar gigantism, let’s take a look at the most blatant example of it,  the colossal squid.

 And I know what you’re thinking, because most people think that the colossal squid is a case of deep-sea gigantism,  but it’s actually not.  Colossal squids are found almost exclusively in the ocean surrounding Antarctica,  and swim in waters close to or even less than zero degrees Celsius.  because of the salinity the water won’t actually freeze a zero degrees but regardless this is still insanely cold and so the squids had to  adapt see colossal squids are actually a type of glass squid which is a family named after a bunch of translucent squids that look like well glass so  why do colossal squids look like anything but a glass squid well this is the polar gigantism taking effect in an environment this cold

 being see-through isn’t that useful.  The colossal squid’s body traded transparency for thick flesh that’s much better for insulation,  but it didn’t actually give up stealth either.  Their bodies have a reddish skin color, which will absorb any possible light from any bioluminescent prey instead of reflecting it,  which means you’ll never see it coming.

 When you’re this big, you don’t really have any predators,  besides the occasional sperm whale, so your body ends up being designed for sneaking up.  rather than sneaking away.  But that still doesn’t answer why the colossal squids are this huge in the first place.  And the answer isn’t in the food down there, but instead in the water itself.

 Cold water holds way more oxygen than warm water does,  and for basically all animals, the larger the body, the more oxygen their cells need to just stay alive.  In warm waters, there just isn’t enough oxygen in the water to support super large creatures.  But when you live at zero degrees, there’s unlimited oxygen.

 And because oxygen is everywhere, their limiter is broken.  Over millions of years, this pushed the glass squids into giants,  or should I say colossals.  And because they then became so big, they literally left behind their glassiness at the same time.  And since larger bodies are better at storing heat and energy,  evolution literally forced these squids to get bigger and bigger,  or die.

 but giant squids don’t live in the polar ocean so how did they get so big see the deep sea gigantism effect does have some relevance here and this  is why giant squids are so giant colossal squids on the other hand live even deeper than giant squids so the deep sea gigantism also plays  a bit of a role but they didn’t get so big solely because of the deep and most of it is because of the cold  Colossal squids are actually a rare case of double crossover gigantism,  combining both polar and deep-sea gigantism into making one really big creature.

 And this is likely why colossals are the largest invertebrates on Earth.  And while not technically longer than the giant squid, they are much heavier,  being over 1,000 pounds, which is double the weight of a giant squid.  but this is just one case of polar gigantism it doesn’t necessarily prove that cold water is creating giants but take a look at this guy this is a normal sea  spider that’s found in a coral reef these guys aren’t actually real spiders since they’re pink nogginids but these sea spiders are about one to two centimeters across

 this is about the same size as your normal house spider but find the same animal in the antarctic ocean and it looks like this  This spider is over two feet across, and is the exact same family as the other tiny spider I just showed you.  So what’s going on here?  Well, the exact same rules that turned glass squids into colossals have forced these spiders to grow bigger.

 Cold water means more oxygen, and these guys literally breathe through their legs.  You can already see how freakishly long they are, so that basically means a ton of oxygen is coming in.  But what can they do now that they’re so big?  Well, unlike crabs or lobsters, giant sea spiders aren’t brawlers,  but they are predators.

 They creep across the seafloor on those massive legs,  using them almost like stilts to step over sponges, corals,  and starfish. They then often use their long proboscis like a straw,  piercing something like a starfish, and then sucking out its insides like a milkshake.  But again, this is the Antarctic Ocean, so the starfish are also ginormous.  I know what you’re thinking, that barely looked like a starfish,  but this is a real starfish, just this one has over 50 arms instead of the normal 5.

 Antarctic starfish are on another level of freaky,  because they didn’t just grow larger, but also evolution literally started stacking on as many arms as it felt like.  Most normal starfish are actually predators too.  and will eat the insides of things like clams.  But Antarctic starfish are so brutal, they’ll literally eat other starfish as well.

 Whoever has the most arms wins, I guess.  Antarctic starfish can also live over 40 years on average,  which is way longer than the five-year lifespan that warm water starfish have.  And yes, this is polar gigantism at play that forced these cute creatures to develop into gigantic freaks.  Funny enough, the effect of polar gigantism is so powerful that it’s also created the longest animal on Earth,  the lion’s mane jellyfish.

 Compare this length to a blue whale, and you can see the lion’s mane is notably longer.  Of course, the blue whale has more mass, but this still goes to show the sheer scale of polar gigantism.  Because if you compare a jellyfish in the same genus as the lion’s mane,  like the blue jellyfish, you can see just how much smaller they are.

 Blue jellies live in warm water, and because of that, were never forced to become massive.  So, after seeing all these oversized monsters of the deep,  you’re probably wondering how high oxygen alone could allow these things to go off the rails.  And while that is a large part of the reason, it’s not the full answer.

 Because the water is so cold, metabolism also slows down massively,  and so much so that large bodies actually become more efficient.  They burn less energy per raw animal mass.  On top of this, the cold ocean is actually extremely…  stable. Which I know is weird because I just showed you a bunch of the giant monsters it has.

 But the temperature barely changes here.  The pressure is constant, and predators are rare.  There’s nothing forcing these animals to stay small and fast.  they can afford to be massive, slow, and built like tanks,  exactly like how the colossal squid developed its strategy.  But you’re probably wondering, if the cold makes things bigger,  then are polar bears a case of polar gigantism, since they’re way bigger than normal bears?  Or penguins, since to be fair, they’re way larger than normal birds?  The thing is, polar gigantism only works for cold-blooded animals,

 which are creatures that let the environment control their body temperature and get their oxygen directly from the water.  For them, colder water means more oxygen, slower metabolism,  and zero energy wasted on generating heat.  Warm-blooded animals, though, are stuck with a different problem.  They have to burn energy constantly just to stay warm,  no matter how cold the water or air gets.

 The bigger they get, the more calories they need.  And in the polar region, there simply isn’t enough food to support something that massive.  Every extra pound of body mass comes with a huge metabolic cost.  So even if they’re not necessarily gigantic, why are they still big?  This has to do with something called Bergman’s rule.

 Bergman’s rule says that in all climates, warm-blooded animals do get bigger.  But not because of oxygen. It’s because larger bodies lose heat slower.  That’s why polar bears are way bigger than other bears, and emperor penguins dwarf tropical birds.  The extra body mass helps them hold on to warmth longer, like having a built-in insulation.

 But there’s a limit. Being warm-blooded means you’re constantly burning energy to stay alive,  so getting too big becomes a massive liability.  The bigger you are, the more food you need, and in the polar regions,  food is already scarce.  This is the same reason woolly mammoths got so big, but never totally out of control.

 So while Bergman’s rule gives you bulk for warmth, it never lets you go full colossal squid mode that polar gigantism gives.  On a much smaller scale, even plankton have their colossal versions.  Antarctic coke pods are basically the polar’s gigantism version of plankton,  and are nearly 10 times heavier than tropical coke pods.

 For reference, most coat pods are so small you can barely see them without a microscope,  since they’re usually not even a millimeter.  Antarctic coat pods can reach up to a centimeter long, big enough that you could actually see swimming with the naked eye.  This obviously isn’t really monstrous like colossal squids are,  but in the eyes of plankton, these things are absolute behemoths.

 But here’s the weirdest part.  Not everything in the polar ocean’s got the gigantism effect.  a select few animals actually got the complete opposite from an effect called polar dwarfism while this is extremely rare and the majority of animals got the  gigantism effect some antarctic fish species like certain ice fish and snail fish are noticeably smaller than their relatives in warmer waters in these extreme  environments food isn’t always available year round  so evolving a smaller body means they can reach adulthood faster,

 reproduce sooner, and survive longer periods of scarcity.  When food is only available for a few months out of the year,  staying small can literally be the difference between life and death,  and having a much faster reproduction cycle will ensure your species survived.  Not really as sick as turning into a giant sea monster,  but still an interesting way evolution made them develop.

 But a weird side effect of the cold is that it doesn’t just change what evolves,  it changes how fast evolution itself occurs.  In the polar ocean, everything runs in slow motion,  which means chemical reactions slow, along with metabolism and reproduction.  A single generation of some Antarctic animals can take decades to complete,  since, as I mentioned, even starfish are now surviving decades instead of just a few years.

 This makes evolution take much longer, and it already takes millions.  millions of years. Many of these species are basically living fossils,  almost identical to their ancestors that swam under the Antarctic ice tens of millions of years ago.  Some sea spiders, urchins, and fish lineages have barely changed since before humans even existed.

 With no drastic seasons in the Antarctic, species here have stayed practically frozen in time for millions of years.  The environment barely changes, so evolution never needed to either.  Every creature here is fine-tuned for a world that’s stable, predictable,  and cold. Which has worked flawlessly for millions of years.

 Literally. But that stability is exactly what makes the Antarctic so fragile.  When your entire ecosystem depends on everything staying the same,  even a small shift can break it.  The moment the environment starts to change, the rules that built these giants start to collapse.  Because being a super mega frost giant sounds really awesome,  until it suddenly isn’t.

 Polar giants have one massive weakness, and it’s that they’re all built for stability,  not change. Their entire existence depends on water that stays freezing,  dense, and packed with oxygen.  Take that away, and the whole system collapses.  Warmer water holds less oxygen, metabolism speeds up,  and suddenly those massive bodies becoming a liability.

 The animals that once ruled the frozen deep start suffocating in their own size.  Bring any of these monsters into a fun, friendly tropical ocean,  and they will literally die from the sunshine.  This is already happening too.  As the oceans warm, oxygen levels are dropping fast, and the creatures that evolved to thrive in the cold are running out of room to survive.

 Studies have shown that sea spider maximum sizes are actually dropping in areas where the water is getting slightly warmer.  And although they’re much harder to study, this means that eventually,  colossal squids could become un-colossal, or just die altogether.  And while I would never actually want to encounter one of these giant monsters face to face,  it’s kinda sad to think about.

 These creatures are living relics from a different world, and regardless,  they’re basically zero threat to us anyways.  Total human death from colossal squids is zero, because no one’s ever been attacked by one.  But anyways, the effect that cold has on evolution is perhaps one of the strangest and most unexpected reasons for gigantism.

 Freeze the ocean and life won’t die.  It just gets giant.  Thanks for watching. And if you want to see a video about the world’s deadliest jellyfish,  check it out here. The most dangerous one isn’t actually the lion’s mane.