Sea otter

Sea otters live in frigid waters from Alaska to California and across parts of Russia. Unlike other marine mammals, they lack blubber, so they rely on the densest fur in the animal kingdom—nearly one million hairs per square inch. Before and after meals, otters groom endlessly, trapping air bubbles between hairs to form an insulating blanket. They wrap themselves in kelp fronds to stay anchored while they sleep, paws tucked under their chins.

Otters forage on the seafloor for sea urchins, crabs, clams, and abalones. Each otter keeps a favorite rock tucked into loose underarm skin that functions like a pocket. Holding prey on their bellies, they smash shells with the rock or use sharp teeth to pry them open. By eating voraciously—up to a quarter of their body weight daily—they control sea urchin populations, allowing kelp forests to thrive and shelter countless fish.

Sea otters live in loose groups called rafts. Mothers give birth in kelp beds, grooming pups until they are buoyant clouds of fur. Pups ride on their mother’s belly while she dives, often leaving the youngster wrapped in kelp to keep it from drifting away. After about six months the pup can dive, hunt, and groom independently. Otters communicate with whistles, squeaks, and playful splashing, and they rub noses when reuniting with friends.

Hunting in the fur trade nearly wiped out sea otters by the early 1900s, but international protection and reintroduction programs have restored many populations. Today, threats include oil spills, coastal pollution, entanglement in fishing gear, and disease carried from land through storm drains. Scientists monitor otters with aerial surveys, attach flipper tags, and test for toxins, while communities reduce runoff and support kelp restoration so these fuzzy marine carnivores can keep sculpting healthy shorelines.