Why do sea otters hold hands?

Sea otters spend most of their lives in the ocean along the North Pacific coast, even sleeping while floating on their backs. To stop currents from carrying them away, they may hold paws with a neighbour or tangle themselves in strands of kelp anchored to the seabed. Resting groups are called rafts and can include dozens or even hundreds of otters. Instead of blubber, sea otters stay warm with the densest fur of any animal, with up to about a million hairs per square inch. They are also famous tool users, cracking open shellfish on rocks balanced on their chests.