Keystone Species

A keystone species is one that is critical to the stability of an ecosystem. Learn about how one keystone species, the sea otter, plays an important role in their environment, why it’s critical to protect their habitat, and how you can help.


Discover how ecosystems work.

Read Chapter 40, Section 1 of E. O. Wilson's Life on Earth to learn how ecosystems function, why balance among each species is so important, and the role of a keystone species.

Life on Earth, Unit 7

Download for free in iBooks

Meet a keystone species.

See how sea otters play a crucial role in their ecosystems in the Pacific Northwest. Learn about the challenges they face by watching two videos: Sea Otters Versus Climate Change and Secrets of the Kelp Forest.

View Secrets of the Kelp Forest in iTunes U Watch Sea Otters Versus Climate Change

CO2 rate of absorption by kelp forests

Before otter protection efforts

After otter protection efforts 12x Higher

Play Again

Illustrate the connections.

Use the app Paper by FiftyThree to write about or draw a picture of the sea otter’s role as a keystone species. Then use RTW Timeline to diagram the events from Sea Otters Versus Climate Change that led to the decline and recent recovery of the sea otter population in the Pacific Northwest. The diagram should show how sea otters, kelp, sea urchins, and humans interact.

“Ecosystems are dynamic: they are defined by change. And they can be delicate. Local ecosystems can collapse and species can go extinct. Yet the living experiment on Earth has persisted for more than 3 billion years.”

- E. O. Wilson's Life on Earth

Celebrate Earth Day.

Learning Materials

Explore the Earth Day collection of apps, books, and more in iTunes.

Customize your lessons

Earth Day Course

Get the assignments and materials for all three Earth Day Lessons in one place on iTunes U.

Subscribe to the course

Apple and the environment

See what Apple is doing to help leave the world a better place.

Learn more