Every Giant Deep-Sea Animal Explained In 12 Minutes

[00:00:00]Giant isopod. A pillbug the size of a house cat. 300 meters below the surface where sunlight fades [snorts] to nothing. This armored scavenger roams the ocean floor in complete darkness. 14 legs, compound eyes with over 4,000 facets, and a body wrapped in overlapping calcium plates like medieval armor. It's basically a woodlouse. The same thing you find under a rock in your garden. Except this one weighs 2 kg and stretches half a meter long. But here's the real trick. When food is scarce, and down here it's always scarce, the giant isopod simply stops eating. Not for days, not for months, for years. One specimen in a Japanese aquarium went 5 years without a single meal. 5 years.

[00:00:46]Just sitting there waiting. And when a whale carcass finally hits the bottom, they swarm it. They gorge themselves so completely that they physically cannot move afterward. Just bloated, armored footballs lying on the seafloor, digesting. If you poke one, it curls into a ball. Same defense as a pillbug.

[00:01:06]Same animal, just scaled up by the abyss. Japanese spider crab. 4 m leg span. The largest arthropod alive.

[00:01:15]Imagine a skeleton made of crab. That's what this thing looks like. Thin, bony legs stretching wider than a car, [snorts] connected to a body the size of a dinner plate. It moves slowly along the ocean floor at 600 m depth, like a giant alien walker from a science fiction movie. Those legs can regenerate, lose one to a predator, and it grows back at the next mol. The body stops growing in adulthood, but the legs, they keep going. Juveniles have a survival trick. They glue sponges and algae to their shells for camouflage.

[00:01:48]Tiny spider crabs wearing costumes to hide from octopuses. Adults don't bother. When you're 4 meters wide, there's not much left to hide from.

[00:01:56][snorts] They can live a hundred years.

[00:01:58]A spider crab born today might still be walking the seafloor in the year 2126.

[00:02:04]In Japan, they call it taka ashi, the [snorts] talllegged crab. and they eat it as a delicacy, though catching one during mating season is illegal.

[00:02:15]Gentle scavenger, terrifying appearance.

[00:02:18]Welcome to 600 meters. Greenland shark.

[00:02:21]The oldest living vertebrae on Earth.

[00:02:24]400 to 500 years old. Let that number land. A Greenland shark alive today could have been born while Shakespeare was writing Hamlet. It was already middle-aged during the French Revolution. And it won't hit sexual maturity until it's 150, 7 m long, grows less than 1 cm per year. Moves so slowly through the Arctic darkness that scientists once called it the sleeper shark. But somehow seal remains show up in its stomach. The theory, it ambushes sleeping seals. Now look at its eyes.

[00:02:55]See those pinkish white things dangling from the cornea? Those are parasitic copapods.

[00:03:01]Omata elongata centimeter long crustaceans that burrow into the shark's eyeball and live there permanently.

[00:03:09]Scientists assume the sharks were blind.

[00:03:12]Recent research says otherwise. Somehow these ancient ghosts can still see parasites and all. And the flesh toxic, loaded with trimethylamine oxide. In Iceland they ferment it for months to make hakarl. One of the most disgusting foods on the planet. A blind toxic five century old ghost shark with worms in its eyes. And we're only at 2,000 meters. Giant orfish 11 meters. The longest bony fish on the planet. Its body is a silver ribbon. Literally. The skin is covered in guanine, the same chemical in DNA, and it reflects light like a mirror. Running along the top, a bright red dorsal fin that looks like a crown of flames stretching the entire length of the body. This is the real sea serpent. For centuries, sailors saw this thing undulating near the surface and told stories about monsters. Japanese fishermen call it Ryugu Notskai, the messenger from the dragon palace. In folklore, when orfish wash ashore, an earthquake is coming. Several appeared before the 2011 To<unk>hoku tsunami. It swims vertically, head up, tail down, drifting like an elevator through the water column. No swim bladder. tiny toothless mouth. It filter feeds on plankton. The most terrifying looking fish in the ocean is basically harmless.

[00:04:36]You almost never see one alive. They surface only when sick or dying. Every confirmed sighting becomes global news.

[00:04:44]Imagine a shimmering silver ribbon the length of a three-story building with a red mohawk floating upright in black water. And before we go any further, subscribe so you don't miss this channel. We have a lot more interesting things to come. Giant phantom jellyfish.

[00:05:01]Fewer than 150 sightings in over 100 years. A meter wide dome, dark reddish brown, nearly invisible in the black water. And hanging below it, four ribbon-like mouth arms stretching over 10 m. Not tentacles, arms. Heavy, dark curtain-like structures that drift and float and wrap around anything they touch. No stingers. This jellyfish doesn't sting. It suffocates. Those arms fold over prey like wet fabric, enveloping it, smothering it, pulling it slowly toward the mouth. Plankton, small fish. Whatever drifts into the curtains doesn't drift out. The dark coloring is camouflage. In a world without light, being dark means being invisible. And here's something strange. This species may skip the polip stage entirely. Most jellyfish alternate between polip and medusa forms. The phantom jelly might give birth to fully formed medusas.

[00:05:57]Ghosts born as ghosts found in every ocean except the Arctic. Yet in a 100 years of deep sea exploration, we've confirmed it fewer than 150 times.

[00:06:09]That's not rare. That's a phantom.

[00:06:12]Colossal squid. Not the giant squid. The colossal squid. Heavier, more dangerous, and armed with weapons the giant squid doesn't have. 495 kg confirmed, potentially 700, the heaviest invertebrate on Earth, lurking in the Antarctic abyss. The giant squid has suction cups with serrated rings. The colossal squid has hooks, sharp three-dimensional swiveing hooks that rotate 360° on its tentacles. They grip, they tear, they don't let go. And the eyes, 30 cm across, up to 40, the largest eyes in the entire animal kingdom, the size of a dinner plate.

[00:06:54]They evolved for one reason, to detect the bioluminescent wake of an approaching sperm whale in total darkness. This is an ambush predator with an absurdly slow metabolism. It doesn't chase, it waits. Hangs in the dark at 2,000 m, and when something comes close enough, the hooks fire.

[00:07:14]We've never seen a healthy adult colossal squid alive in its natural habitat.

[00:07:20]Everything we know comes from dead specimens, stomach contents of sperm whales, and a few lucky deep water camera encounters.

[00:07:28]Giant pyrosome 18 m long, the size of a city bus. And it's not one animal, it's a colony. Hundreds of thousands of tiny cloned creatures called zooids embedded in a gelatinous tube, all working together. Each one is a few millime.

[00:07:45]Together they form a hollow translucent cylinder that drifts through the ocean like a living tunnel. The name means fire body because it glows. The entire colony produces bioluminescent light.

[00:07:59]Green, pink, blue, green, visible from meters away. Touch one part and the glow ripples across the whole structure like a wave. A bus-sized neon tube pulsing in the dark ocean. They feed by pumping water through the colony and filtering out microscopic plankton. And they can move slowly by coordinated jet propulsion from all the zoids at once.

[00:08:23]Millions of tiny organisms firing in unison, pushing an 18 m tube through the sea. When they die, they sink. And that sinking matters. Pyrosome falls deliver enormous amounts of organic carbon to the deep seafloor, feeding entire ecosystems below. Divers who've been inside one describe it as swimming through a living light tunnel. The walls glow around you. You're inside an organism. Organisms. Millions of them.

[00:08:52]Big fin squid. The most alien looking creature in the ocean. Imagine a body the size of a grapefruit. Now attach tentacles that stretch 8 m, 20 times the body length, and hold them out at perfect 90° elbows, like a marionette, like a puppet dangling in the void. This squid lives below 4,000 m. The deepest confirmed sighting, 6,212 m in the Philippine trench. That's the deepest any squid has ever been recorded. The Hadel zone, the edge of the abyss. Since it was first described in 1998, there have been fewer than a few dozen confirmed sightings. Every single one from a remotely operated vehicle camera. Every single one producing footage that looks more like a horror film than a nature documentary.

[00:09:40]Those tentacles aren't for chasing prey.

[00:09:42]They're fishing lines. The squid hangs motionless in the water. Arms dangling, sticky filaments waiting for anything.

[00:09:50]Plankton, small crustace to drift into contact. A passive trap in infinite darkness. The body is gelatinous, adapted to the crushing pressure. The fins are enormous relative to the mantle, hence big fin. But it's the posture that haunts you. That perfect unnatural 90° bend. Like something designed to be terrifying.

[00:10:16]Super giant amphipod. The evolutionary absurdity of the abyss. A normal amphipod, the kind you find on a beach or in a stream, is a few millime, a sand flea, a speck. Aloella Gigantia is 34 cm, foot long, the size of a rabbit.

[00:10:35]That's like a human growing to 300 m tall. [snorts] Same body plant, same basic anatomy, just scaled up by the crushing dark. It lives at 5,000 to 7,000 m. The abyssal and hallel zones found in the Mariana Trench, the deepest point on Earth. A pale, [snorts] elongated, shrimplike scavenger with reduced eyes, crawling across the seafloor in perpetual darkness, waiting for dead things to fall from above.

[00:11:03]Scientists recently sequenced its genome. It's enormous. One of the largest genomes of any crustation. The theory, the huge genome might be directly linked to the huge body. More DNA, more building instructions, more growth. And here's the final twist.

[00:11:20]Despite being found at the most extreme depths on the planet, recent surveys suggest Alysella Gigantia might inhabit 59% of the world's oceans. Not rare, not isolated. Everywhere under our feet, in the dark. The deeper you go, the bigger they get. And the abyss is just getting started.