Sea otters often hold hands while floating so that they do not drift apart in sleep.

The longer version

Sea otters wrap kelp around themselves or grasp a companion's forepaw to stay anchored, since drifting apart in currents would separate a pair and cost energy to repair. Groups resting together are called rafts, and a raft may hold a dozen or more animals, with males often gathering apart from females and pups.

The behaviour also protects pups, which float but cannot yet swim well. Mothers carry pups on their chests while resting. Anchoring with kelp is common in kelp forests, where the plants provide a natural mooring in open water. The habit has been photographed often enough to become a familiar image, though the underlying reason is simply staying in place.

Where this entry sits

This collection gathers curious details about sleeping and dreaming, from nightly brain stages and body clocks to naps, yawns and unusual animal habits. It also covers how bedtime customs have changed across centuries, without offering any advice. The full list sits on the Sleep and Dreams page, where every entry is listed in order.