The More the Deep Sea Takes Away, the Stranger Animals Get

Sink a camera into the ocean, past the last of the  sunlight, and something unsettling happens. The   animals stop looking like animals. This octopus  flies on its ears. Fins, technically. This squid   has elbows. And they're not even the strangest  story down here. Somewhere in the dark lives the   animal most often linked to the kraken. Thousands  of dives into the Gulf of Mexico never caught   sight of it. Then a team tried the opposite. No  bright lights. Just a camera hiding in the dark,   and in front of it, a fake jellyfish. Then  something reached for it. Why does the deep do   this to them? The first thing the deep takes from  you is light. As you sink, the sunlight thins into   a blue haze. A little past three thousand feet,  it's gone for good. Along the way, the water   strips out the colors, and red goes first. Which  is why so many animals down here are red. Under a   robot's lights, this jellyfish is blazing. Switch  them off, and there's no red light left to bounce   off it. It's black. A few of these jellyfish  even make their own light, like this one, called   Atolla. But hiding has a catch. If everyone is  invisible, how does anyone find dinner? You bring   a lamp. The dots around this squid's eye are light  organs. When researchers counted the animals they   filmed in open water, three out of four could make  light. Down here, glowing is the default. They   hunt with it and find a mate with it. Weirdly,  they also hide with it. Some light up their   bellies to match the faint sunlight above, so a  hunter looking up sees nothing. Some went further   and turned into glass. You can see straight  through this squid, to its insides floating   in a bag of glass. It's nearly perfect camouflage,  with a single flaw: the eyes. An eye has to catch   light to see, so it can't be clear. A few glass  squids fix that with lights underneath their eyes,   to cancel out the shadow. But camouflage can't  fill a stomach. Keep sinking, and hiding stops   being the big problem. Eating is. Next, the deep  takes the food. No sunlight, no plants. Most of   the food down here started near the surface and  sank. Those white specks drifting past this squid   have a name, marine snow: dead plankton, scraps,  and, to be honest, plenty of waste. It's gross,   and it's also dinner. Of all the food made near  the surface of the open ocean, about one part in   a hundred reaches the seafloor. The deep lives on  crumbs. So what do you do with a menu like that?   You wait. This guy found a fish head. He's a giant  isopod. At an aquarium, keepers watched a giant   isopod go more than five years without eating.  Honestly, I find that more disturbing than any set   of teeth in this video. Others set a trap instead.  The anglerfish sits on its rock and does nothing.   The thin rod on its head used to be a fin spine.  Now it's a fishing rod, with bait on the end. It   goes fishing with its own face. Out in open  water, some dragonfish shine red light, a   color most animals down here can't see. A private  flashlight: it sees you, and you never see it.   But the strangest way to live on crumbs is  to slow your whole life down, and for that,   it helps to be cold. Keep sinking, and the deep  takes the warmth. Most of the deep ocean sits   a few degrees above freezing, about as cold as  your fridge. A mile down, the pressure is more   than a hundred and fifty times what you feel  right now. So how does anything soft survive   that? Our friend with the ears, the dumbo  octopus, has no air-filled spaces in its   body. Nothing to collapse. Dumbos live deeper  than any other octopus. The record is more than   four miles down. Flapping. Completely relaxed.  Easily the cutest animal in this video. Other   animals down here get huge. The giant isopod,  a relative of the woodlouse in your garden,   is as long as your forearm. The cold is a suspect:  it slows growth and stretches life. But everything   we've seen so far still runs on the sun. What  lives where the sun isn't part of the deal at all?   In a few places on the seafloor, even the crumbs  from the sunlit surface stop mattering. The food   chain starts from something else. Within living  memory, nobody knew this existed. Scientists went   looking for warm water on the seafloor. Instead,  they found a crowd: crabs, clams and giant worms,   living in total darkness. Nobody had expected a  crowd like that, so there wasn't a single deep sea   biologist on the expedition. Every food chain on  Earth was supposed to start with the sun. So what   are these animals eating? That smoke is seawater  that soaked into hot rock below and came back   out loaded with chemicals. Microbes turn those  chemicals into food, the way plants use sunlight,   and everything else lives off the microbes. Which  is how you get this: shrimp, packed onto the rock   beside a vent. And the animal from the start? It  was hiding somewhere we'd already been. The eerie   part is where the giant finally turned up. Not  down here at the bottom. On the very first floor,   in the dim water where the light runs out. We sank  right past it, and so did every dive in the Gulf   before this one. For centuries, sailors told of a  giant with arms long enough to drag a ship down:   the kraken. Giant squid are the animal most often  linked to those stories. Dead ones washed up on   beaches, so we knew they existed. But almost  nobody had seen them alive, in the deep,   where they live. Why not? Part of the answer  is a little embarrassing. We kept bringing the   lights. Robots dive with bright white lights, and  those can scare animals away. So a team brought   a camera that had already worked once: years  earlier, off Japan, it filmed a giant squid.   No bright lights and no noisy thrusters. Only red  light: the dragonfish's trick, borrowed. In front   of the lens: a fake jellyfish that flashes blue.  That flash copies Atolla, the little red jellyfish   from the first floor. When Atolla is attacked, it  lights up like a burglar alarm, and the flash may   call in something bigger to eat whatever is eating  it. You bite me, I call your predator. So the team   faked a cry for help, and waited to see who would  answer. On the fifth try, something did. The fake   jellyfish raised the alarm, and something big  came to look. These are its arms. A giant squid,   at least ten feet long, filmed alive in  American waters for the first time. The kraken,   it turns out, doesn't drag ships down. It comes  when a jellyfish raises the alarm. So, why does   the deep do this to them? Because the deep gives  almost nothing, and every strange body we've   seen is built from whatever was left. The kraken  came out once we played by its rules: darkness,   and a small flash of light. And the last detail?  The team thought it was still young. At the start,   I said the animals down here stop looking like  animals. I was wrong: they're built for the dark.   We've barely explored this ocean, and somewhere  out there, the grown-ups are still waiting.