Case Study – Sea Urchins, Kelp Forests, and Consservation

What if one small, furry animal could decide the fate of an entire ecosystem? That’s the story of the sea otter, a species once hunted nearly to extinction for its valuable fur, and now celebrated as a hero of the ocean. This case study resource is designed to bring that powerful story into the biology classroom and help students explore one of the most important ecological concepts: the keystone species.

Sea otters (Enhydra lutris) are more than just cute faces floating on their backs. They are critical predators in coastal food webs, keeping sea urchin populations in check. Without sea otters, sea urchins overgraze kelp, turning vibrant underwater forests into barren wastelands. With sea otters present, kelp thrives, biodiversity increases, and the whole ecosystem remains in balance. This real-world example gives students a memorable way to understand how keystone species shape ecosystems.

What’s Inside the Case Study

This resource provides a four-part exploration of sea otters:

• Introduction and History: Students learn how hunting reduced sea otters to near extinction, and how their biology makes them uniquely adapted to their environment.
• Population Data: A look at population changes over time, with opportunities for students to analyze recovery trends.
• Keystone Connections: An in-depth exploration of the relationship between sea otters, sea urchins, and kelp forests.
• Laws and Recovery Efforts: How conservation measures and legal protections helped sea otters make a comeback.

Related Resources

Article: What is a Keystone Species? – Article with reading comprehension questions exploring keystone species

Trophic Cascades – Uses an interactive activity at HHMI to explore trophic cascades in a variety of ecosystems

The Crayfish Project – Explore crayfish as an invasive species with this set of lessons that ends in a dissection

Sea Otter Plush – Use this toy to grab their attention and to introduce sea otters

Lutrinology – Learn everything there is to know about sea otters with this “Ologies” Podcast