Plankton Eat Plankton World
Written by: Colleen Miks
Illustrated by: Sabine Deviche and James Baxter

show/hide words to know

Apex predator: an animal that is at the top of the food chain, that is not preyed upon by any other non-human animal.

Aquatic: living in either fresh or salt water.

Ecosystem: a group of different plants and animals that live together and are dependent on the area in which they live.

Organism: a living thing that can be small like bacteria or large like an elephant.

Photosynthesize: to carry out photosynthesis, the process of using the sun’s energy to turn carbon dioxide gas into sugars... more

Phytoplankton: photosynthetic plankton that are usually microscopic and are also called “algae"... more

Zooplankton: small, sometimes microscopic animals that live in water and feed on phytoplankton (algae), other zooplankton, or detritus (dead material)... more

Water dropInside a drop of water that you might collect from a stream, river, lake or ocean are tiny organisms. These tiny and sometimes not so small living things are called plankton.

What role do plankton play in aquatic food webs? What do plankton eat, and what uses plankton as a food source? As you learned in Invisible Watery World,there are two different types of plankton, phytoplankton and zooplankton.

All other life in the ocean needs phytoplankton to survive. Phytoplankton get their energy directly from the sun using photosynthesis, just like plants. Zooplankton then feed on phytoplankton, and are then eaten by larger zooplankton, fish, larger fish, and so on. Plankton are at the base of a complex aquatic food web.

During this activity you will learn how to create your own food web. You will also analyze the feeding relationships between marine organisms and describe plankton’s importance to the ecosystem.

What You Need

  • Marine Food Web worksheets (Download PDF)
  • Colored Pencils
  • Scissors
  • Yarn
  • Glue

Before You Begin

  • Print out the Marine Food Web worksheets.
  • Color and cut out the marine organisms on the “Marine Organisms” page.
  • Read “Invisible Watery World” and look at the “What do I eat?” table.

Now it is time to begin building your Marine Food Web!


suns energy goes to phytoplanktonStep 1: You will use the yarn to show how organisms are connected in your food web. Start with the phytoplankton that you colored and cut out. You will glue the phytoplankton to your “Marine Food Web” worksheet. The sun provides phytoplankton the energy needed to survive. Represent the relationship between the sun and phytoplankton with a piece of string.

Step 2: Draw an arrow to show the direction the energy moves. Arrows represent energy flow from one organism to the next so make sure that your arrow faces the right direction. The sun gives energy to phytoplankton, so the arrow faces phytoplankton, as shown.

phytoplankton's energy goes to zooplanktonStep 3: Which organisms consume phytoplankton to gain energy for survival? Zooplankton. Just like in steps 1  and 2, you will represent this relationship by connecting the phytoplankton and zooplankton with a piece of string, and draw an arrow to show the energy flow. Make sure your arrow is pointing in the right direction.

Step 4: Keep adding organisms, using the “What do I eat?” table to figure out what each organism eats. Add organisms until you reach one that is not consumed by any other organism. That organism is called an Apex Predator.

Step 5: You will have some cut-out organisms that are not part of your food web. That’s okay! Start again with the sun and add on each organism just like you did before. Keep adding arrows to show which way the energy flows. When you run out of organisms, you are done.

The end result will be a Marine Food Web!

Colleen Miks received her Bachelors of Science in Fisheries Biology from Humboldt State University. She received her Masters of Education from Plymouth State University and teaches Earth and Space Science at Sossaman Middle School in Gilbert Arizona.

This Ask A Biologist activity was funded by NSF Grant Award number 0752592 and 1030345.

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Bibliographic details:

  • Article: It’s a Plankton Eat Plankton World
  • Author(s): Colleen Miks
  • Publisher: Arizona State University School of Life Sciences Ask A Biologist
  • Site name: ASU - Ask A Biologist
  • Date published: May 28, 2013
  • Date accessed: April 17, 2024
  • Link:

APA Style

Colleen Miks. (2013, May 28). It’s a Plankton Eat Plankton World . ASU - Ask A Biologist. Retrieved April 17, 2024 from

American Psychological Association. For more info, see

Chicago Manual of Style

Colleen Miks. "It’s a Plankton Eat Plankton World ". ASU - Ask A Biologist. 28 May, 2013.

MLA 2017 Style

Colleen Miks. "It’s a Plankton Eat Plankton World ". ASU - Ask A Biologist. 28 May 2013. ASU - Ask A Biologist, Web. 17 Apr 2024.

Modern Language Association, 7th Ed. For more info, see
Planktonic Organisms

This activity has a companion article on Plankton. Discover an Invisible Watery World in water full of creatures too small to be seen!

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