Good morning. My presentation is about one of the smallest marine mammals on the California coast, the sea otter, and why scientists call it a keystone species.

A keystone species is one whose effect on its surroundings is much larger than its numbers would suggest. Take it away, and the whole system changes shape.

Sea otters eat sea urchins, which are small, spiny animals that feed on kelp. Kelp is a giant seaweed that grows in underwater forests, and those forests shelter hundreds of kinds of fish and other animals.

When otters were hunted for their fur in the eighteen hundreds, they disappeared from most of the coast. With no otters to eat them, the urchins multiplied. They chewed through the bases of the kelp, and in many places the forests were replaced by bare rock covered in urchins. Divers call these places urchin barrens.

A small group of otters survived along the Big Sur coast. Once they were protected, they slowly spread. In the stretches of coast the otters reached, the kelp grew back. In stretches they did not reach, many barrens remain.

So when people ask why it matters to protect one small animal, my answer is that we are not really protecting one animal. We are protecting the forest it keeps standing.