Who's in Charge? Wolves, Otters, and the Ripple Effect Through Food Webs

Shared by A STEM Educator

7th Grade5E Model50 min

Learning Objective

Students will be able to trace energy flow through a food web, explain the role of apex predators in maintaining ecosystem balance, and predict the cascading effects of removing a top predator using evidence from real-world examples.

Lesson Overview

Students investigate how energy flows through food webs and what happens when an apex predator is removed, using real-world case studies from Yellowstone wolves and Pacific kelp forests to understand trophic cascades.

Materials

Paper (1 sheet per student)
Pencils
Whiteboard and markers

Scaffolded Task Progression

1Task 1

Read this claim: 'When wolves were removed from Yellowstone in 1926, the rivers changed course.' Write your prediction: Do you believe this is possible? Why or why not? Use what you know about food chains to support your thinking.

2Task 2

Using the organisms on the board (Wolves, Elk, Willows/Grasses, Berries, Bears, Ravens, Coyotes, Mice, Hawks), draw a food web on your paper. Draw arrows from prey to predator (energy flows toward the eater). Then label each organism with its trophic level (Producer = Level 1, Primary Consumer = Level 2, etc.) and circle the apex predator.

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