to keep from drifting away at rest The sea otters use the kelp to hide from the predators. Then they prey on sea urchins, which travel in "herds" and graze on kelp and could destroy a kelp forest if too many are present. The less sea urchins the less harm will come to the kelp forests. They wrap themselves in kelp so they can rest there and not worry about floating away. It is possible they drape themselves in kelp to hide from predator and prey alike as well.