How Do Fish Breathe Underwater? Ocean Animal Adaptations Activity

Investigate how fish breathe underwater by simulating a gill in this hands-on science experiment for kids learning about ocean animal adaptations.

Ocean Animal adaptations activity

When I teach my science unit on habitats and ecosystems, we spend a lot of time discussing and learning about animal adaptations. Animals in every type of habitat have special features that help them to survive in their environment.

This ocean animals adaptations experiment focuses on a well-known fish adaptation: gills. Gills are a special body part that fish have to allow them to absorb dissolved oxygen from water in order to breathe.

A fish’s gills are similar to a filter. Water goes into a fish’s mouth, then is pushed out of the fish’s gills. As the water goes through the gills, the gills filter dissolved oxygen from the water, and that oxygen moves into the fish’s blood to allow it to survive.

How Do Fish Breathe Underwater?

This experiment helps students to visualize the process of the gills working in a fish’s body.

Start with a video

To get students thinking about the ocean animals adaptations, I start by showing the video How Do Fish Breathe Underwater?

Then I explain to students that they will be given materials to use to demonstrate how gills help a fish breathe. The quick video helps get students thinking about what types of materials might be able to represent this process.

How do fish breathe underwater experiment

This activity is a simulation that represents a simplified version of how gills work. It helps students to visualize the oxygen in water. In order to simulate breathing underwater, the Kool-Aid represents oxygen dissolved in water passing through the gill (coffee filter) and into the fish’s body (cup).

Materials:

coffee filter
2 clear plastic cups
packet of Kool-Aid or any colored drink powder
paper towels
water
rubber band
lab sheet

Lab sheet source

Have students work in small groups or partners for the experiment.

After watching the video, ask students: “How can you use these materials to show how a gill works and helps a fish breathe underwater?” Guide students to see that they can use the Kool-Aid to represent dissolved oxygen and the coffee filter to represent the gill it passes through.

Procedure:

1.Gather your materials. Write what each material represents on your lab sheet.

2. Next, fill 2 cups 1/3 full of water. Place a coffee filter over the top of one cup and secure it with a rubber band.

3. Using the cup of water without the filter, pour a very small amount of Kool-Aid into the second cup and watch it dissolve.

4. Once the Kool-Aid is dissolved, carefully pour the Kool-Aid water slowly over the coffee filter to demonstrate water with dissolved oxygen passing through the gills into the fish’s body. Be careful not to overfill the cup as you pour!

After completing the demonstration, students record their observations in writing on their lab sheet. Finally, students explain how the simulation represents gills enabling a fish to breathe underwater.

Lab sheet source

Get this lab with lesson plans

This lab is part of a complete unit on habitats and ecosystems that include everything you need to teach animal adaptations. This 3-week unit includes a 7-lesson teaching PowerPoint, STEM activities, science experiments, journal and center activities, and MUCH more!

These high-engagement are available in printable, digital with narrated audio lessons, and a bundle version:

Click here to see the yearlong 2nd grade science curriculum.

I hope you and your students are able to enjoy this How Do Fish Breathe Underwater experiment! It can help to really bring students’ understanding about ocean animals adaptations to life. Be sure to pin this post for easy access when you are planning!