How Do Marine Animals Control Buoyancy?
How do marine animals float, sink, or remain suspended in the ocean? The answer comes down to buoyancy—the same scientific principle that helps a massive ship like the Battleship USS IOWA stay afloat.
In this STEM education video, Battleship USS IOWA Museum and Cabrillo Marine Aquarium in San Pedro, California, explore the science of animal buoyancy and the fascinating ways marine organisms adapt to life in the ocean.
The lesson looks at how marine animals manage their position in the water and introduces students to plankton—tiny organisms whose size, shape, density, and other adaptations can help them remain suspended rather than quickly sinking.
Students can then put the science into action through a hands-on plankton engineering challenge. Using simple household materials, participants design their own model plankton and test how slowly they can make it sink through water. The challenge encourages students to experiment with weight, shape, surface area, and design while practicing the engineering process of building, testing, observing, modifying, and testing again.
What Students Learn
Through the activity, students explore:
- What buoyancy is and how it works
- How marine animals adapt to different ocean environments
- Why plankton need adaptations that help control sinking
- How shape, weight, density, and surface area affect movement through water
- How scientists and engineers use observation, experimentation, and iterative design to solve problems
The lesson also demonstrates how closely maritime engineering and marine science are connected. From tiny plankton drifting through the ocean to the 45,000-ton Battleship USS IOWA floating at the Port of Los Angeles, the principles of buoyancy are all around us.
This educational collaboration between Battleship USS IOWA and Cabrillo Marine Aquarium brings together maritime history, ocean science, and hands-on STEM learning to help students discover the science of the sea.
Watch the video below and then try the plankton buoyancy challenge yourself.
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