Koko:
Owlo! Owlo! I have the most exciting news. I went to the aquarium yesterday with my family!
Owlo:
Oh, how wonderful, Koko! The aquarium is such a magical place. What was your favorite part?
Koko:
The big fish tank! There were so many fish swimming around. They were so fast and colorful and beautiful.
Owlo:
That does sound amazing. Fish are truly fascinating creatures.
Koko:
But Owlo, I kept watching them and watching them, and I had a big question. How do fish breathe underwater? They never come up for air!
Owlo:
That is one of the best questions I have heard this week, Koko. Let us head to the science lab and find out together.
Owlo:
Here we are! Now, Koko, do you know what you need to breathe?
Koko:
Um, air? I breathe air. I can feel it going in through my nose.
Owlo:
Exactly right. And inside the air, there is something very special called oxygen. Our bodies need oxygen to live.
Koko:
Oh yes! My mom told me oxygen is in the air. But there is no air underwater, so how do fish get it?
Owlo:
Great thinking! Here is the secret. Water actually has tiny bits of oxygen hiding inside it. We just cannot see them.
Koko:
Wait, really? Oxygen is hiding in the water? That is so sneaky!
Owlo:
It really is! And fish have a special body part that pulls that hidden oxygen right out of the water.
Koko:
What body part? Is it their fins? I love their little fins.
Owlo:
Not the fins, but a very good guess. The special part is called gills. See this picture in our science book here.
Koko:
Ohhh, those feathery looking things on the sides of the fish? I saw those at the aquarium!
Owlo:
Those are the ones! Gills work a little bit like our lungs. Our lungs take oxygen from air. Gills take oxygen from water.
Koko:
So gills are like fish lungs, but for water! That is so cool.
Owlo:
That is a perfect way to think about it, Koko. Now, let me show you how it works. Take this cup of water.
Koko:
Okay, I have the cup. What do I do with it?
Owlo:
A fish opens its mouth and takes in water. Then the water flows over the gills. The gills grab the oxygen from the water.
Koko:
And then what happens to the water after the gills take the oxygen out?
Owlo:
The water goes back out through small openings on the sides of the fish. You can see those openings in the picture.
Koko:
Oh! So the fish drinks water in, takes the oxygen, and then pushes the water back out. Like a little breathing machine!
Owlo:
What a brilliant way to describe it, Koko. That is exactly what happens, every single second the fish is swimming.
Koko:
So the fish never has to stop and come up for air because it gets everything it needs from the water around it.
Owlo:
Precisely. The water is full of oxygen, and the gills are perfectly made to collect it. Fish and water are a perfect team.
Koko:
I wish I had gills. Then I could swim underwater forever and ever.
Owlo:
That would be quite an adventure. But your lungs are perfect for living on land, and that works out very well for us.
Koko:
This is so much to remember. Owlo, can I try to say back everything I learned today?
Koko:
Okay! Fish breathe underwater using special parts called gills. Water has tiny oxygen hiding inside it. The fish takes water in through its mouth, the gills grab the oxygen, and the water goes back out the sides. So fish never need to come up for air because they get oxygen straight from the water. And also, gills are basically fish lungs, which is the coolest thing ever.
Owlo:
That was a perfect summary, Koko. I am very proud of you. Next time you visit the aquarium, you will know exactly what those gills are doing.
Koko:
I am going to tell my mom and dad all about gills tonight. And maybe next we can learn about how fish swim so fast, because some of those fish were super speedy!
Owlo:
Now that is a wonderful idea for our next adventure together. The ocean has so many more secrets waiting for us.