Ocean Food Web

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Author: Tricia Edgar

Peer into an underwater world. What’s on the menu in the ocean café? In this cool science fair project, discover how tiny ocean life feeds some of the largest animals on the planet.

Problem: What plants and animals are part of an ocean food web?


  • 8½” x 11” square piece of white cardstock paper
  • Colored pencils
  • Pen
  • Ruler
  • Scissors
  • Transparent tape
  • Books about the plants and animals of the ocean
  • String
  • Masking tape
  • Push pins
  • Corrugated cardboard

The oceans are huge, covering almost three quarters of the earth’s surface! They’re also extremely rich with life; in fact, we know much less about life in the ocean than we do about the animals and plants that live on land.

Whales are one of the most recognizable marine mammals, and people love to visit the Pacific Northwest to go whale-watching. One of the most famous whales in the Pacific Northwest is the killer whale, or orca. Some of these black and white whales eat fish, but others, known as the transient orcas, eat other marine mammals such as seals. Transient orcas move from place to place, while resident whales stay in the same general part of the ocean.

Ocean Food Web Orca

Seals are common in the Pacific Northwest, and they will often pop up next to you if you’re in a boat.

Ocean Food Web Seal

These marine mammals like to munch on fish as well—usually fish like herring or salmon.

Ocean Food Web HerringOcean Food Web Salmon

What do little herring fish eat? They survive on plankton—the tiny, drifting animals and plants in the ocean. There are two broad types of plankton: phytoplankton is a plant, while zooplankton is an animal.

Ocean Food Web Phytoplankton

The herring prefer to eat little zooplankton called copepods.

Ocean Food Web Copepods

It’s hard to believe that something as tiny as a copepod needs a good food supply, but copepods have to eat too! They forage on other plankton, algae, dead plant materials, and bacteria.

Can you think of other plants and animals that live in the ocean? What do they eat?


In this activity, you’ll build a food chain, web, and pyramid. You may have heard the terms food chain, food web, and food pyramid. What do they mean, and how are they different? A food chain is a simple chain that illustrates which organisms eat which. In a food chain, you begin with one plant. In the ocean, this might be one of the very abundant phytoplankton. A grazing copepod might eat the phytoplankton, and a herring would come along and eat the copepod for lunch. After that, a seal looking for its supper would find a few delicious herring and munch on them. If you wanted to go further, you could add your orca whale into the food chain, which likes to eat the seal.

Ocean Food Web Diagram

Creating a Food Chain

  1. To create a food chain, place a foot-long piece of string on the cardboard. Pin it at either end.
  2. Create labels that say “phytoplankton,” “copepod,” “herring,” and “seal” and add these labels to push pins.
  3. Place the plant pin at one end of the string, followed by the copepod, the herring, and the seal.
  4. You’ve created a food chain—a simple line that shows how one plant can feed a copepod, which feeds a herring, which then feeds a seal.
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