Winter Fishtival: Marine Mammal Fun Facts

Join us for hands-on activities, special talks and opportunities to learn more about the care and feeding of the Aquarium's fish, birds, tide pool animals and marine mammals during Winter Fishtival! Each day we'll highlight a different sea animal and activity. Today the featured animals are the marine mammals. Here are some fun and interesting facts about river otters, sea otters, harbor seals and Northern fur seals.


River Otters

River otters (Lutra canadensis) are related to badgers, weasels, and skunks. Like other members of the family, they are carnivores and have anal scent glands that secrete musk.

Physical Characteristics:

  • Size: smaller than sea otters
    • Male river otters average between 20-30 lbs. and 3-5 ft. in length, including tail.
    • Female river otters average slightly less in weight and length than males.
  • River otters are adapted to living on land. They are nimble land runners, but their streamlined body, long, pointed tail and webbed toes make them fast swimmers as well.

Behavioral Characteristics:

  • River otter common habitat: Found in both marine and fresh water. In coastal habitats, they are found in estuaries, marshes and the lower parts of streams. Inland, river otters are found in lowland marshes and swamps, streams and small lakes. They make dens in shrubbery, along river banks, or in abandoned beaver, badger, fox or rabbit dwellings.

Cool Facts:

  • River otters are clean but scented animals (due to their musk glands).
  • Very social and “playful” animals that love to climb and slide.
  • Like sea otters, river otters need to frequently groom their fur to maintain water resistance. You may see river otters “squeegeeing” off the water against a hard substrate on land.


Sea Otters

Sea otters (Enhydra lutris) are the smallest of all marine mammals and are members of the weasel family.

Physical Characteristics:

  • Male Northern sea otters average between 70-100lbs and 4.5ft in length, including tail. Female Northern sea otters average between 40-60lbs and 4ft in length, including tail.
  • Like seals they spend some time on land and retain a relatively well developed sense of smell.
  • Contrast to seals:
    • Lack insulating blubber and rely on their thick fur and on food to maintain body heat.
    • Sea otters have paw-like front limbs and rear flippers, while all four seal limbs are modified to form flippers.

Behavioral Characteristics:

  • Sea otter common habitat: live in rocky coastal areas near points of land where some areas are protected from wind and waves. They prefer kelp beds, but they are not essential.
  • Social animals, sea otters gather in rafts (groups) ranging from a few dozen to over 100 animals. Rafts are sexually segregated (females avoid male feeding areas).
  • Roll and whirl in the surf to remove food scraps and debris. They rub, comb and rake their fur with their forepaws; then roll in the water to smooth the fur and wet the tips.

Cool Facts:

  • Within every square inch of a sea otter’s fur there are approximately 500,000 hairs. That equals the number of hairs on 2 or 3 entire human heads!
  • When moving rapidly, sea otters swim on their bellies; otherwise they are normally seen swimming or resting on their backs. They can dive up to 300ft and remain underwater up to 4-5 minutes to hunt for food.
  • There are more than 50 kinds of marine invertebrates that sea otters eat (mussels, clams, abalone and other snails, octopuses, crabs, sea urchins, and sea stars). But usually sea otters specialize in only two to four kinds of prey.


Northern Fur Seals

Northern fur seals (Callorhinus ursinus) are adapted for terrestrial and aquatic life. In the order Pinnipedia (modified limbs to flippers) and family Otariidae.

Physical Characteristics:

  • External ear flaps, rotation of rear flippers under its body, use of fore flippers for propulsion and hind flippers for steering, numerous hairs in fur and use of lots of vocalization.
  • Size: Male northern fur seals average between 350-600 lbs. and 2 meters in length. Female northern fur seals average 95-110 lbs. and 1.5 meters in length.
  • Males are four to five times larger than the females, one of the greatest size differentials of any mammal.
  • Their ability to rotate their rear flippers forward and to extend their front flippers forward allows 4-legged movement -- hence their family name of “walking seals.”
  • Have a thick layer of blubber which contributes to their streamlined shape, provides buoyancy, and stores energy. The northern fur seal depends also on a fur density of some 300,000 hairs per square inch.

Behavioral Characteristics:

  • Northern fur seal common habitat: Common offshore during migration, rarely in inside waters. They have a migratory range from the Mexican border to the Pribilof Islands in Alaska (200 miles north of the Aleutian chain).

Cool Facts:

  • Both males and females are present in Washington State offshore waters from November –June – rarely hauling-out on land and instead sleeping on the surface of the ocean some distance from shore.
  • They can dive up to 673ft and remain underwater over 7 minutes to hunt for food. Nostrils remain closed unless consciously opened.
  • Northern fur seals go to the Pribilof Islands in Alaska or the Commander Islands in Russia in July to have pups and to mate, females come usually a day before giving birth. They usually go to the same territory every year. In fact, they have such a strong attachment to their breeding ground that they continued to use the same areas even when sealers drove some of them to near extinction.


Harbor Seals

Harbor seals (Phoca vitulina) are members of the true seal group. They comprise a generally inquisitive, but elusive, species which spends equal time on land and in the sea. These seals are not limited to salt water and have been found in inland waterways and lakes. In the order Pinnipedia (modified limbs to flippers) and family Phocidae.

Physical Characteristics:

  • No external ear flaps, hind flippers cannot be rotated forward and are used for propulsion underwater, front flippers used to help steer in water and for locomotion on land, fur provides little insulation, thick blubber layer and use little vocalization.
  • Inability to utilize hind flippers for locomotion on land, instead using front flippers and body undulations, leads to their family common name of “crawling seals.”
  • Size: Male harbor seals average of 250-300lbs and 5-6ft in length. Female harbor seals average of 200-250lbs and 4-5ft in length.
  • Have a thick layer of blubber which contributes to their streamlined shape, provides buoyancy, and stores energy.

Behavioral Characteristics:

  • Harbor seal common habitat: coastal and inland marine waters and estuaries, areas where sandbars, beaches or rocks are uncovered at low tide for hauling out.
  • Harbor seals have no definite migrations but will move in search of food.
  • Adults are solitary, except during breeding, and rarely interact outside of sexual encounters. During breeding times, they are communal in not engaging in gender segregation.

Cool Facts:

  • The harbor seal is the only seal that breeds in Washington and is the most abundant marine mammal in the waters of Puget Sound.
  • They can dive up to a maximum of 1000ft and remain underwater up to 23 minutes to hunt for food. Nostrils close naturally when diving and must be consciously opened to breathe.
  • Harbor seals will sleep on land or just below the water surface. If underwater, the seal will come up to breath every 5-10 minutes without waking up.

Come visit the Aquarium to learn more about marine mammals at Winter Fishtival. Tomorrow’s featured animal is the coral reef!

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