These adorable, furry marine mammals--often seen floating on their backs holding hands--reveal the health of the coastal ecosystem along the Pacific Ocean. Once hunted for their prized fur during the 1700s and 1800s, these animals nearly went extinct. Only now, nearly a century after hunting ceased, are populations showing stable growth in some places. Sea otters are a keystone species in coastal areas, feeding on sea urchins, clams, crab, and other crustaceans. When they are present, kelp beds are thick and healthy, providing homes for an array of sealife. When otters disappear, sea urchins take over, and the kelp disappears along with all of the creatures that live in the beds. Now, thanks to their protected status, sea otters are making a comeback in California, Washington, and Alaska.