Join the Seattle Aquarium for Winter Fishtival, where we’ll feature different sea animals and fun activities each day. Our focus on January 3 will be marine mammals: river otters, sea otters, northern fur seals and harbor seals. (Be sure to come visit our harbor seals when they return to the Aquarium for the opening of our new harbor seal exhibit in June!) There’s lot to learn—and love—about these charming creatures. See below for a few interesting facts, then come to the Aquarium to learn more!
How do you tell the difference between a river otter and a sea otter? River otters are smaller than sea otters (males average 20–30 pounds and 3–5 feet in length; females are slightly smaller). And, unlike sea otters, river otters are adapted to living on land. They’re nimble runners but their streamlined bodies, pointed tails and webbed toes make them fast swimmers as well.
Unlike most other marine mammals, sea otters don’t have a thick blubber layer to help them stay warm. Instead they rely on air trapped in their incredibly dense fur: on average, a square inch of sea otter fur contains approximately 500,000 hairs—about the same number of hairs as two or three human heads. To maintain the fur’s insulating qualities, sea otters frequently groom. They roll in the water to rinse off food scraps and debris; then rub, comb and rake the fur with their forepaws; then roll in the water again to blow air bubbles into their fur.
Northern fur seals
Like harbor seals, fur seals have a thick blubber layer that provides insulation and enhances buoyancy. But fur seals also stay warm with the help of trapped air in their thick fur (approximately 300,000 hairs per square inch). Fur seals and sea lions are referred to as “walking seals” because they can achieve four-legged movement when they rotate their rear flippers forward and extend their front flippers. Male fur seals are four to five times larger than females; one of the greatest size differentials of any mammal.