How Deep Is the Ocean? A Trip to the Bottom 🐙 | Tutki’s Big Journey

How deep is the ocean, really, and what lives at the very bottom? 🐙 The ocean is Tutki’s home, but even Tutki has never been all the way down. So he ties a foam cup to his eighth arm and sinks, through six stops, to the deepest place on Earth. Where does the light run out, and why does Tutki’s orange disappear first? How do fish survive pressure that would crush a submarine? Why does so much deep-sea light glow blue, and which fish shines a secret red searchlight? How can anything live with no sunlight at all? And what will the deep do to that cup? ▶ Try it yourself, free: https://nowiseewhy.com/salty-sea?from... An interactive 3D lesson for ages 5–11, with a Grown-ups level too. No accounts, and no ads in the lessons. Chapters 0:00 How deep does it go?! 1:00 Stop 1: The sunlit zone 2:33 Stop 2: The twilight zone 3:51 Stop 3: The midnight zone 6:27 Stop 4: The hot springs 7:52 Stop 5: The abyss 9:59 Stop 6: The deepest place 12:32 What happened to the cup? 12:55 The whole trip 13:44 Try it: the squirting bottle 14:27 Fun facts! The ocean is about eleven kilometres deep at its deepest known spot. Near the top, the sunlit zone (down to about 200 m) is the only part with enough light for plants: tiny drifting phytoplankton, which make about half of Earth’s oxygen. Sea water soaks up sunlight’s colours one by one: red goes first, in the top few metres, then orange and yellow, so red and orange things look dull and dark only a little way down; blue reaches deepest. Water pressure grows by about one more atmosphere every ten metres: about 20 times the air’s at 200 m, about 200 times at 2,000 m, and more than 1,000 times at the bottom. In the twilight zone (about 200–1,000 m), huge crowds of animals rise toward the surface every night to feed and sink back before sunrise: the biggest migration on Earth. Sperm whales can dive deeper than a kilometre to hunt squid, holding their breath for an hour or more. Below about 1,000 m, no sunlight reaches at all. Most deep-sea animals make their own light, mostly blue, the colour that travels furthest through sea water. A deep-sea anglerfish’s lure glows with bacteria living in it; the stoplight loosejaw, a dragonfish, makes red light that most deep-sea fish can’t see; the vampire squid squirts a cloud of glowing, sticky mucus instead of ink, and dumbo octopuses have no ink at all. Deep-sea animals aren’t crushed because they’re mostly water, which hardly squeezes, and have no air spaces like lungs; a body chemical called TMAO helps their proteins work under pressure. Hydrothermal vents are hot springs on the seafloor: sea water seeps into cracks, is heated by hot rock and gushes out hotter than 350 °C without boiling, because of the pressure; the black ‘smoke’ is minerals turning solid. Nearly fifty years ago, scientists in a small submarine found vents crowded with life. Giant tube worms have no mouth or stomach: bacteria inside them make food from chemicals in the vent water (chemosynthesis), with no sunlight. The abyss (deeper than about 4,000 m) has wide, flat plains of soft mud. Marine snow (bits of dead plankton, poop and dust) can take weeks to fall there and feeds much of the deep. A whale fall can feed a community for decades; bone-eating ‘zombie worms’ have no mouth or stomach. The deepest octopus ever seen, a dumbo octopus, was almost 7,000 m down. One deep-sea octopus guarded her eggs for about four and a half years, the longest known for any animal. About 150 years ago, sailors measured depth with a weighted rope; today ships use sonar (sound travels about 1.5 km a second in sea water), and only about a quarter of the seafloor has been mapped up close. Satellites map the rest roughly, from tiny bumps on the sea surface made by the pull of undersea mountains. Over sixty years ago, two people reached the deepest point in a steel sphere, a trip down of nearly five hours. The deepest fish ever filmed is a snailfish more than 8,000 m down; no fish has been found deeper than about 8,400 m. At the very bottom, amphipods crowd onto bait, and a plastic bag has been found almost eleven kilometres down. Foam cups taken down by deep-sea subs come back a fraction of their size: the pressure squeezes the air out of the foam. Got a "why" question? Ask a grown-up to send it at https://nowiseewhy.com/ask The voices in this video are AI-generated. #TutkisBigJourney #DeepSea #ScienceForKids