Sea otter

The sea animal that holds hands while sleeping

The sea otter eats floating on its back: it puts a stone on its belly and cracks shells against it! So the current doesn't carry them away while sleeping, otters hold each other's paws or wrap themselves in kelp. Their fur is the densest in the world — 150,000 hairs per square centimetre. A mother carries her pup on her belly.

The sea otter (Enhydra lutris) is the smallest marine mammal (30 kg), living along the northern Pacific coasts (Alaska, California, Kamchatka, the Kurils). It has no blubber — dense fur (150,000 hairs/cm²) and constant grooming keep it warm; oil that ruins the fur is fatal. One of the few tool-using animals: it cracks crabs, sea urchins and shells with a stone. A 'keystone species': by eating urchins it protects kelp forests, which shelter fish and absorb CO₂. Nearly wiped out for its fur in the 18th–19th centuries (2,000 left), now about 125,000; IUCN: Endangered.

Fun facts

• A sea otter carries its favourite stone in a 'pocket' under its arm!
• Its fur is so dense that its skin never gets wet.
• Sea otters sleep wrapped in kelp so the current cannot carry them off.