Why do sea otters hold hands while sleeping?

Sea otters float on their backs, and if they are resting in a current or rough water, they can separate easily from a group. Holding hands or anchoring in kelp helps them stay together and avoid drifting. Kelp forests are especially important because they provide food, shelter, and a natural anchor. Sea otters also have the densest fur of any mammal, which keeps them warm because they lack a thick layer of blubber. Their behavior became widely known through photographs and videos, though the hand-holding is partly about stability rather than affection alone.