Eared seal
Marine mammals with visible ears, including sea lions and fur seals.
Eared seals, also known as otariids or otaries, are members of the marine mammal family Otariidae, one of three groupings of pinnipeds. They comprise 15 extant species in seven genera (another species became extinct in the 1950s) and are commonly known as sea lions or fur seals, distinct from true seals (phocids) and the walrus (odobenids). Otariids are adapted to a semiaquatic lifestyle, feeding and migrating in the water, but breeding and resting on land or ice. They reside in subpolar, temperate, and equatorial waters throughout the Pacific and Southern Oceans, the southern Indian, and Atlantic Oceans, and are conspicuously absent in the north Atlantic.
- classification
- Family Otariidae, order Carnivora
- extant species
- 15 species in 7 genera
- extinct species
- 1 species (extinct in the 1950s)
- distinguishing feature
- Small but visible external ear flaps (pinnae)
- sexual dimorphism
- Males weigh 2 to 6 times as much as females
- diet
- Carnivorous: fish, squid, and krill
Lore & Background
Otariids arose in the Miocene (15–17 million years ago) in the North Pacific, diversifying rapidly into the Southern Hemisphere, where most species now live. The earliest known fossil otariid is Eotaria crypta from southern California, while the genus Callorhinus (northern fur seal) has the oldest fossil record of any living otariid, extending to the middle Pliocene. Traditionally, otariids had been subdivided into the fur seal (Arctocephalinae) and sea lion (Otariinae) subfamilies, with the major distinction being the presence of a thick underfur layer in the former. However, molecular studies do not support this traditional division, and the subfamily separation has been removed entirely, with the family now organized into seven genera with 16 species and two subspecies.
Reader's Guide
Eared seals are significant as a major group of pinnipeds, distinct from true seals and walruses due to their visible external ear flaps and ability to walk on all fours on land. They are generally considered less adapted to an aquatic lifestyle than phocids, breeding primarily on land and hauling out more frequently, yet they can attain higher bursts of speed and greater maneuverability in the water. Their swimming power derives from the use of flippers rather than the sinuous whole-body movements typical of phocids and walruses. Historically, fur seals were commercially exploited for their thick underfur. The family's evolutionary history, including the debate over whether phocids diverged from otariids before or after the walrus, and the recent molecular evidence that has removed the traditional subfamily divisions, highlights ongoing scientific refinement of pinniped taxonomy. Their polygynous breeding behavior, with males establishing territories and females giving birth shortly after arriving on shore, varies among species, from herding harems to controlling spatial territories.
Did You Know?
- The words 'otariid' and 'otary' come from the Ancient Greek ὠτάριον (ōtárion), meaning 'little ear'.
- Otariids are conspicuously absent in the north Atlantic.
- The earliest known fossil otariid is Eotaria crypta from southern California.
- Female New Zealand sea lions are the only otariids that move up to 2 km into forests to protect their pups during the breeding season.
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