How Do Sharks Float?

Introduction

Sharks are incredible ocean animals that come in many different sizes. Some sharks, like the dwarf lantern shark, are tiny enough to fit in your hand, while the whale shark can grow as long as a bus and weigh more than 20 tons! But have you ever wondered how such a huge animal can float in water without sinking?

Unlike many fish, sharks do not have a swim bladder to help them float. Instead, they rely on special body features such as lightweight cartilage, strong fins, and a large oily liver. In this STEM activity, students will explore how a shark’s oily liver helps it stay buoyant in water.

                                  

STEM Activity: How Do Sharks Float?

Materials Required

• 2 small bottles or balloons
• Vegetable oil
• Water
• Large bowl
• Permanent marker (optional)

Step-by-Step Procedure

Step 1: Prepare the Bowl

To get started you will need to fill a bowl with water. Make sure you do not fill the water all the way to the top of the bowl. Leave some space at the top of the bowl so the water does not spill over when you add something to the water. This way the water will stay in the bowl. The water will not overflow 

Step 2: Fill the Bottles

• Fill one bottle with water.
• Fill the bottle with vegetable oil.
• Make sure to close both bottles so they do not leak.

Step 3: Decorate Your “Sharks” (Optional)

To make the bottles look like sharks use a marker to draw fins and eyes and gills on the bottles. This will make the bottles look like sharks. Use a marker to draw the fins and the eyes and the gills, on the bottles to make them look like real sharks. 

Step 4: Place Them in Water

Put both bottles into the water in the bowl. Watch what happens.

• Do the bottles go down to the bottom of the water? Do they stay on top?
• Does one bottle stay higher up, in the water than the bottle?
• Which bottle stays higher up in the water, the bottle or the second bottle?

Observation: What Do You Notice?

Students will notice that:

• The bottle that is filled with water sinks lower in the bowl.
• The bottle that is filled with oil floats better and it stays closer to the surface.

This happens because the oil is lighter and the oil is less dense, than the water.

Scientific Explanation

Sharks have a big liver that is almost a quarter of their whole body. This liver has a kind of oil in it called squalene. Squalene is not as heavy as the water in the sea so it helps the shark stay up in the water. This makes sharks stay up easily and not sink down.

Sharks also have some things that help them:

• Cartilage instead of bones which makes their body lighter.
• Strong fins that help them swim through the water, like how airplane wings go through the air.

If sharks did not have that liver they would have to use a lot more energy to keep swimming and stay up in the water.

Real-Life Applications

Learning about shark buoyancy is really helpful to scientists and engineers in a lot of ways. They can use this knowledge to design submarines and underwater robots. Shark buoyancy also helps them study how marine animals move. It helps them understand ocean ecosystems too. This knowledge is also useful for improving exploration technology.

Scientists want to learn how animals, like sharks, adapt to their environment. Marine biologists also study sharks to better protect ocean life and understand sea habitats. They do this by learning more about shark buoyancy and how it affects the ocean and the animals that live there including sharks.

Why This Activity is Important for Students

This science project is really cool for students because it helps them learn about things like density and buoyancy.

• They get to understand how animals adapt to their surroundings.
• Students also develop skills like observing things and thinking like a scientist.

This project shows students how the science they learn in class is used in the world to study marine biology. It makes them curious about ocean animals and the ecosystems they live in. Hands-on experiments are a way to make science more fun and easier to remember for students.

Conclusion

Sharks are cool animals that have some very special things about them that help them live in the ocean. The liver of a shark is full of oil. This helps the shark stay up in the water.

This is a thing you can try at home or in school to see how things float in water and it can help you understand how sharks are able to survive in the ocean. You can do some things to learn about science and this can be a great way to learn about animals and the ocean and how things work.

You never know this might just make someone want to study sharks when they get older and become a shark biologist. 

FAQ

1. Why don’t sharks sink?

Sharks have an oily liver, lightweight cartilage, and fins that help them stay buoyant in water.

2. What is squalene?

Squalene is a special oil found in a shark’s liver that helps it float.

3. Why did the oil bottle float better?

Oil is less dense than water, so it floats more easily.

4. Do sharks have bones?

No. Sharks have skeletons made of cartilage, which is lighter than bone.

5. What does buoyant mean?

Buoyant means able to float in water without sinking.

6. What can students learn from this activity?

Students learn about density, floating, animal adaptations, and marine science through hands-on experimentation.