Found along the rocky coasts of British Columbia, the sea otter is a small marine mammal that plays an outsized role in the health of the Pacific kelp forest. Unlike seals and sea lions, which keep warm with a thick layer of blubber, the sea otter has almost no body fat at all. Instead, it relies entirely on its fur to survive the cold North Pacific water. Once hunted close to extinction for that very fur during the fur trade, the sea otter vanished from Canadian waters for most of the last century before being carefully reintroduced to the British Columbia coast in the 1970s.

The sea otter's most remarkable feature is its coat, which is the densest fur of any animal on Earth. A single sea otter may carry up to a billion hairs, packed so tightly that water never reaches the skin. Because the fur alone keeps the animal warm, the sea otter must groom constantly to trap a layer of air against its body. This dense coat is what made the species so valuable to hunters, and it is also what allows even a newborn pup to float on the surface like a cork while its mother dives for food.