Why does the ocean have tides?

Have you ever wondered why the ocean creeps up the beach and then slides back out every single day? It is not magic—it is gravity! Join Mira and Finn as they uncover the wild secrets of the sea. You will discover how a giant rock floating in space—the Moon—actually pulls the Earth's water to create high and low tides! We'll even learn what happens when the massive Sun joins in for a giant game of tug-of-war. But the adventure doesn't stop at the sunny beach! We are taking a high-tech submarine dive straight down into the freezing, pitch-black Midnight Zone! Did you know there are fish that make their own light? Meet the wild anglerfish with a glowing, bacteria-filled fishing rod growing right out of its head! Plus, you'll come face-to-face with the legendary giant squid, an enormous creature with eyes the exact size of a dinner plate! From glowing ocean predators to the unbelievable crushing pressure of the deep sea, you will never look at the ocean the same way again. Grab your submarine gear and let's dive in!

Transcript

SPEAKER_00 0:00

Welcome to Science Is Not Boring by kidopoly.com. I'm Mira. And I'm Finn. Before we dive in, we have a huge shout out to Mitchell and Callie in Milford, Connecticut.

SPEAKER_01 0:12

Congratulations on graduating preschool. That is awesome.

SPEAKER_00 0:16

Mitchell and Callie listened to all the shows and asked us about the ocean and tidal waves. So this one is totally for you. Wait.

SPEAKER_01 0:24

Since summer is starting and everyone is heading to the seaside, are we finally talking about the beach?

SPEAKER_00 0:30

We are, but we are also going to the deepest, darkest parts of the ocean. Imagine an eye the size of a dinner plate staring at you in pitch black darkness. A dinner plate? No way. Whose eye is that big? A giant squid's! And the craziest part is, the very same ocean that giant squid swims in is being pulled around by a giant rock in the sky. You mean the moon? Exactly! Today we are talking about why the ocean has tides and the weird, glowing creatures that live in the deep dark sea.

SPEAKER_01 1:04

Okay, so I know the sea creeps up the beach and slides back out twice a day. That's the tide. But how does the moon do that? It's literally in space.

SPEAKER_00 1:15

It is really far. The moon is 238,900 miles away. If you could drive a car straight up at 60 miles per hour, it would take you almost six whole months to get there.

SPEAKER_01 1:28

I would need so many snacks for that road trip.

SPEAKER_00 1:32

Definitely! But even from that far away, the moon has gravity, and that gravity pulls on everything on Earth. But it doesn't pull me up into the sky. I don't float away when the moon comes out. That's because Earth's gravity is pulling you down much harder. But liquid water is different. The ocean isn't a solid block, so it can swish and stretch. The moon's gentle pull actually stretches the water into two giant bulges, one pointing right at the moon and one opposite.

SPEAKER_01 2:03

Like two giant water bumps covering the planet.

SPEAKER_00 2:06

Exactly! Now, picture the Earth spinning. As it spins, the continents move. Your favourite beach spins right into one of those big water bumps, giving you high tide.

SPEAKER_01 2:18

Oh, so the water isn't actually rushing onto the beach. The beach is spinning into the water.

SPEAKER_00 2:24

You got it! And about six hours later, your beach spins out of a bump, making it low tide. That makes so much sense.

SPEAKER_01 2:32

But wait, don't we sometimes get super extreme tides?

SPEAKER_00 2:36

Yes, we do. That happens when the sun gets involved. The sun is 93 million miles away, but it's so massive that it also pulls on our oceans.

SPEAKER_01 2:47

What happens if the sun and the moon pull at the same time?

SPEAKER_00 2:49

When the sun, earth, and moon line up perfectly straight, their gravities combine like a giant tug of war team. This creates extra big, extreme tides called spring tides.

SPEAKER_01 3:01

That is a mind-boggling amount of water moving around. Does all that splashing affect the creatures living down in the deep dark sea?

SPEAKER_00 3:09

Well, to find out what's going on down there, we have to leave the sunny beach and dive straight down. Way, way down into the darkness.

SPEAKER_01 3:17

How far down are we talking? I don't like the dark. Even my closet freaks me out sometimes.

SPEAKER_00 3:24

We are sinking way past the sunlight zone. Down, down, down, past 3,300 feet, where the last tiny, glittering bit of sunlight completely vanishes.

SPEAKER_01 3:37

3,300 feet? That is more than half a mile, straight down. I can't hold my breath that long.

SPEAKER_00 3:45

Don't worry, we are in a high-tech submarine. Welcome to the Midnight Zone, or the Bathypelagic Zone. It stretches from 3,300 feet all the way down to 13,100 feet deep.

SPEAKER_01 4:02

What's the weather like down there?

SPEAKER_00 4:04

Freezing! The temperature stays around 39 degrees Fahrenheit all year long. And remember, there is absolutely zero sunlight. It is pitch black.

SPEAKER_01 4:16

If they can't see anything, how do the fish find food? Or friends?

SPEAKER_00 4:22

They make their own light. It's an incredible trick called bioluminescence. Imagine looking out the submarine window into total blackness and suddenly seeing a tiny, glowing neon blue light hovering in the water. Ooh, is it a friendly little deep-sea fairy? Nope. That light belongs to a female anglofish. She has a built-in fishing rod made of bone that grows right out of the middle of her forehead. Ew, a fishing rod growing out of her head! Yes, and at the very tip of that rod is a glowing fleshy bulb called an esker. The anglofish dangles this glowing lantern in the dark to trick hungry little fish into coming closer, thinking it's a glowing snack.

SPEAKER_01 5:09

And then she eats them with those crazy jagged teeth that look like broken glass. But wait, how does the esker glow? Are there batteries in there?

SPEAKER_00 5:19

It's so much weirder than batteries. The esker is filled with millions of tiny, glowing bacteria. Wait, the fish is teaming up with glowing germs. Exactly, it's a partnership. The bacteria get a safe, cozy home inside the fish's lure, and the anglofish gets a free glowing flashlight to catch her dinner. Plus, her stomach can expand to swallow fish twice her own size.

SPEAKER_01 5:46

A bacteria flashlight and an expanding stomach? That is equally awesome and completely terrifying.

SPEAKER_00 5:53

The anglofish is definitely cool, but look closer out the submarine window. Something massive is drifting through the black water.

SPEAKER_01 6:02

Massive? How massive? Like a school bus?

SPEAKER_00 6:07

Pretty close. It can be over 40 feet long from the tip of its head to the end of its tentacles. And it can weigh around 600 pounds. We've just found a giant squid.

SPEAKER_01 6:20

Whoa!

SPEAKER_00 6:21

Is that the one with the crazy huge eyes? Yes! The giant squid has some of the largest eyes in the animal kingdom. They are up to 11 inches across. That is the exact size of a large dinner plate. Or a frisbee. A dinner plate?

SPEAKER_01 6:39

My eyes are the size of grapes. Why in the world does a squid need eyes the size of a dinner plate?

SPEAKER_00 6:45

To survive its worst nightmare, the sperm whale. Sperm whales are huge mammals that hold their breath and dive down thousands of feet just to hunt giant squids in the dark.

SPEAKER_01 6:58

But if the midnight zone is completely pitch black, how do giant eyes help? You can't see in the dark, no matter how big your eyes are.

SPEAKER_00 7:07

That's where the glowing animals come back into the story. When a massive sperm whale swims through the midnight zone, it bumps into thousands of those tiny glowing jellyfish and bacteria we talked about. Oh, does it make the whale light up? Exactly! It creates a sparking, bioluminescent outline of the whale, zooming through the dark water. The giant squid's dinner plate eyes are perfectly designed to catch that extremely faint glow from up to 400 feet away.

SPEAKER_01 7:39

Wow! So the squid sees the glowing outline of the whale and knows it's time to run away.

SPEAKER_00 7:45

Yes, it gives the squid a head start to shoot a jet of water and blast away into the darkness. Scientists have even found giant squids with sharp serrated suckers on their tentacles for fighting back.

SPEAKER_01 7:58

The deep sea is wild. It's like a totally alien planet down there, filled with glowing bacteria and squid battles.

SPEAKER_00 8:06

It really is. But the most beautiful part is that the freezing water surrounding that giant squid is the exact same ocean that the moon is pulling up onto your beach right now. It's one amazing connected system.

SPEAKER_01 8:22

So the moon is basically stirring up the ocean for everyone. From the sunny beach all the way down to the deepest, darkest trenches.

SPEAKER_00 8:29

Yes! Tides do so much more than just wash away sandcastles. They act like a giant mixer for the ocean. They pull nutrients from the coast out into the sea, feeding microscopic plankton, which feeds the fish, which feeds everything else.

SPEAKER_01 8:45

The moon is putting in a lot of hard work up there in space.

SPEAKER_00 8:48

It sure is. And the friction from all that ocean water sloshing around actually acts like a giant brake pad on the Earth. It's slowing down Earth's spin very, very slightly. Days are getting longer by tiny fractions of a second.

SPEAKER_01 9:03

Wait, the moon is making my school day longer? I'm going to need to have a talk with the moon.

SPEAKER_00 9:10

It's only a few milliseconds every century, so you won't even notice it. But speaking of wild facts, did you know the ocean isn't the only thing the moon's gravity pulls? It also pulls the solid ground.

SPEAKER_01 9:23

What?

SPEAKER_00 9:24

The ground moves like an earthquake. It's called an earth tide. The solid crust of the earth under your feet bulges up and down about 12 inches twice a day, just like the ocean. We just don't feel it because the whole continent is moving up and down together.

SPEAKER_01 9:40

Hold on, I'm riding a slow-motion dirt wave every single day. My brain is officially blown.

SPEAKER_00 9:47

I thought you'd like that. And I've got one more crazy fact about the midnight zone where the squid lives. It's about the pressure.

SPEAKER_01 9:54

Oh right, all that water stacked up above them.

SPEAKER_00 9:57

Exactly. Down in the midnight zone, the weight of the water pushing down is roughly 5,800 pounds per square inch. 5,800? How heavy is that? Imagine taking a full-grown African elephant, turning it upside down, and having it balance its entire body weight on your thumb. That is how hard the water is squeezing everything down there.

SPEAKER_01 10:22

Ew, my poor thumb. That would squish me flat as a pancake. How do the squids survive that?

SPEAKER_00 10:29

Their bodies are mostly made of water, and water doesn't compress easily. Since they don't have air-filled lungs or bones like we do, the pressure doesn't squish them.

SPEAKER_01 10:39

Good for them, but I'm definitely staying up here on the dry, solid ground. Even if it is bobbing up and down 12 inches a day.

SPEAKER_00 10:46

Alright, Finn, it is time for the quiz. Are you ready to test your ocean knowledge?

SPEAKER_01 10:52

I think so. But I feel like I am under 5,800 pounds of pressure right now.

SPEAKER_00 10:58

You'll do great. First question. What celestial body pulls on the ocean to create the regular tides? Next one. What do we call the extra big extreme tides when the sun and moon line up perfectly? Question three. What is the glowing bacteria-filled fishing lure on an anglerfish called? Here's number four. Exactly how big is a giant squid's eye? Last question. How deep down in the ocean does the pitch black midnight zone start? Great job! Let's see how you did. The first answer is, the moon's gravity creates the regular tides. For question two, those extra big tides caused by the sun and moon are called spring tides. The answer to question three is the glowing lure is called an escher. For number four, a giant squid's eye is the size of a dinner plate, or up to 11 inches across. And the final answer is the midnight zone begins at 3,300 feet deep.

SPEAKER_01 12:21

Phew! I survived the quiz, the giant squids, and the crushing pressure of the midnight zone.

SPEAKER_00 12:28

You did awesome! Science is just so cool, right? One minute we are looking up at the moon in space, and the next we are staring at a glowing fish deep in the ocean.

SPEAKER_01 12:39

Yeah, it's wild how everything is connected. Though I still think the glowing bacteria flashlight is totally gross.

SPEAKER_00 12:46

Hey listeners, if you loved learning about the deep dark sea today, please leave us a five-star review. Just scroll down on your podcast app and tap the stars. Yeah, please do it for the giant squid. It has its dinner plate eyes on you. Oh, and don't forget to head over to our site kidopoly.com. We have tons of fun learning games, activities, and more cool stuff to explore there.

SPEAKER_01 13:11

And if you want your name on the show, like Mitchell and Callie, or if you just want to say hi, send us an email at hello at kidopoly.com.

SPEAKER_00 13:20

Thanks for listening, and see you next time on Science is Not Boring. Bye, everyone.