SCIENCE • SEA LIFE

How do fish breathe underwater? 🐠

You need air to breathe. If you stay underwater too long, you run out of air. But a fish can live underwater its whole life and never come up for air!

Let's discover the fish's amazing secret: gills. Tap Next to dive in! 🤿

Secret 1: There is air inside water 💨

The part of air we need to breathe is called oxygen. Here's the surprise: tiny bits of oxygen are floating dissolved inside the water too — you just can't see them!

Where do you think fish get their oxygen from? Tap the correct answer.

☁️ From the sky above the sea 💧 From oxygen dissolved in the water 🍚 From the food they eat
Pick one — it's okay to try again!

Secret 2: Gills are the fish's "lungs" 🌬️

Instead of lungs, a fish has gills — feathery red parts on each side of its head, hidden under a flap. Tap each glowing part to learn what it does!

👆 Tap the mouth, the gill flap, or the red feathery gills.

Secret 3: Water flows in one door, out another 🚪

A fish keeps water moving over its gills. Water goes in the mouth ➜ over the gills ➜ out the gill flap. Tap the button to help the fish pump water!

mouth in flap out

Oxygen collected: 0 of 5 gulps

Secret 4: A tiny swap happens 🔄

Inside the red gills, blood does a clever swap with the water:

Oxygen moves into the blood 👍  |  waste gas carbon dioxide moves out into the water 👋

Drag each token into the right box. Which goes into the fish, and which comes out?

⬅️ INTO the blood
OUT to water ➡️
🟢 Oxygen ⚪ Carbon dioxide 🟢 Fresh oxygen
Drag a token onto a box.

Secret 5: Why a fish can't breathe air 😮

Gills only work when they are wet. Out of water, the feathery gills stick together and dry out — so they can't grab oxygen, even though there's lots of air around!

Sort these animals: does it breathe with gills or with lungs? Tap to sort.

🐟 Fish 🐶 Dog 🦈 Shark 🧒 You 🐬 Dolphin
Tap an animal, then it will ask gills or lungs.
🌊 Gills
🫁 Lungs
🐟🎉

You cracked the fish's secret!

Here's how a fish breathes underwater:

Fun fact: Sharks must keep swimming so fresh water keeps flowing over their gills — some would suffocate if they stopped! 🦈

Well done, young scientist! Now you'll never look at a fish tank the same way again. 🐠✨