These sea otters in Alaska are floating amid kelp—an important flora friend to the endangered marine mammals. Sea otters live mostly in the water and use the thick blades of kelp to anchor themselves as they sleep and to keep their buoyant pups from floating away. Just as the kelp helps otters, sea otters help the kelp, too. They ensure the kelp"s survival by eating sea urchins. If sea urchin populations are left unchecked, these spiny vacuum cleaners of the sea destroy kelp forests by munching on holdfasts that tether kelp to the ocean floor. The resulting clear-cut areas, called urchin barrens, are devastating to the overall ecosystem. Kelp forests provide food and safe harbor for hundreds of fish species and other sea creatures. They also remove carbon dioxide from the air, a benefit to us all.