These intelligent and social animals congregate in large groups on land (called colonies) and smaller groups in the water (called rafts). Breeding areas are called rookeries.

Anatomy: The Northern Fur Seal has tightly-rolled external ears. This pinniped can rotate its hind flippers forward, like sea lions (but unlike true seals). This seal can "walk" on land using all four flippers. It has a thick layer of blubber (fat), and a bear-like head. The short, thick fur is dark brown-gray to black (when wet); there can be lighter areas on the throat and chest. The whiskers on the snout (called vibrissae) help the seal's sense of touch. The nostrils are closed in the resting state. The Northern Fur Seal has a good sense of hearing. It also has keen eyesight but no color vision. Males (called bulls) are much bigger than females. Bulls weigh 450-600 pounds (200-275 kg) and average 6.8 feet (2.1 m) long. Females weigh 90-110 pounds (40-50 kg) and are up to 4.5 feet (1.4 m) long.

Diet: Northern Fur Seals are carnivores (meat-eaters) that hunt at night (they are primarily nocturnal). They eat fish, squid, and octopi. Seals don't chew their food; they swallow it in large chunks.

Predators: Northern Fur Seals are hunted by killer whales (orcas), some sharks, foxes, and Steller sea lions.

Classification: Suborder Pinnipedia, Family Otariidae (eared seals), Subfamily Arctocephalinae (fur seals), Genus Callorhinus, Species ursinus. This seal was first described by Georg Wilhelm Steller in 1742.