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Eared seal

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Eared seals belong to the marine mammal family Otariidae. They are part of a larger group called pinnipeds. This group also includes true seals, known as phocids, and walruses, known as odobenids. People commonly refer to otariids as sea lions or fur seals. The name "otary" comes from the Ancient Greek word "ōtárion," which means "little ear." This name describes their visible external ear flaps, or pinnae. These small flaps distinguish them from true seals, which lack external ears.

Sea lion family
Sea lion family

Otariids have a semiaquatic lifestyle. This means they live partly in water and partly on land. They use the ocean for migrating and feeding on prey. However, they must return to land or ice for resting and breeding. Their bodies are built for movement in both environments. They have large fore-flippers and strong pectoral muscles. These features allow them to turn their hind limbs forward. Because of this, they can walk on all fours on land. In the water, they use their flippers for power. This makes them very maneuverable and capable of high bursts of speed.

Sea lion family
Sea lion family

Scientists use different categories to group these animals. Traditionally, otariids were divided into two subfamilies: Arctocephalinae, the fur seals, and Otariinae, the sea lions. The main difference was the presence of a thick underfur layer in fur seals. However, recent genetic evidence has changed how we classify them. Many studies suggest the subfamily separation may be invalid. For example, the northern fur seal is actually more closely related to some sea lions. Today, the family Otariidae is organized into seven genera and 16 species. Despite these scientific changes, the terms "fur seal" and "sea lion" are still useful. They help describe differences in hair, size, and behavior.

Sea lion family
Sea lion family

There are many distinct differences between fur seals and sea lions. Fur seals are generally smaller than sea lions. They also have a thick layer of underfur. This fur historically led to commercial exploitation by humans. Fur seals tend to take longer foraging trips far offshore. They usually eat smaller prey items during these trips. Sea lions have coarser, shorter hair. They typically stay closer to shore in upwelling zones. There, they feed on larger fish.

Sea lion family
Sea lion family

The history of the otariid family spans millions of years. They likely arose during the Miocene epoch, about 15 to 17 million years ago. Evidence suggests they first appeared in the North Pacific. From there, they diversified and moved into the Southern Hemisphere. Most otariid species live in the Southern Hemisphere today. The earliest known fossil is named Eotaria crypta from southern California. The genus Callorhinus, which includes the northern fur seal, has the oldest fossil record. This record extends back to the middle Pliocene.

Sea lion family
Sea lion family

Otariids show extreme differences between males and females. This is called sexual dimorphism. In many species, mature males weigh two to six times as much as females. They also have much larger heads, necks, and chests. Sizes vary greatly across the family. The Galápagos fur seal is the smallest otariid. In contrast, the Steller sea lion is much larger. A male Steller sea lion can weigh over 1,000 kg.

Sea lion family
Sea lion family

Breeding behavior is a major part of the otariid life cycle. Most species are polygynous, meaning successful males breed with several females. Most species form annual groups on beaches or rocky areas. They follow a strict yearly breeding season. The Australian sea lion is an exception with a 17.5-month cycle. Males often arrive at breeding sites first to establish territories. They use vocal displays, visual signals, or fighting to hold these areas. Some species, like the northern fur seal, herd females into groups. Others, like the Steller sea lion, control specific spaces instead.

Sea lion family
Sea lion family

Diet and hunting habits vary by species. All otariids are carnivores. They eat fish, squid, and krill. They are visual feeders, meaning they use their eyes to find food. Some female otariids are capable of diving to depths of 200 meters. This allows them to reach prey in deeper waters. Their survival depends on these specialized hunting skills and their ability to move between the sea and the land.

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