How are true seals different from sea lions and fur seals?

True seals (family Phocidae) are distinct from sea lions and fur seals (family Otariidae) due to several key anatomical and behavioral differences.1

Key Differences

• Ears: Sea lions and fur seals have visible, external ear flaps, which is why they are often called "eared seals." True seals lack these flaps, possessing only small ear holes, leading to their classification as "earless seals".1
• Locomotion: Sea lions and fur seals have long front flippers and can rotate their back flippers forward under their bodies, allowing them to walk on land. In contrast, true seals have short front flippers and cannot rotate their back flippers; consequently, they must move on land by flopping on their bellies.1
• Swimming Style: When swimming, true seals propel themselves by moving their back flippers side to side like a fish tail. Sea lions and fur seals use their long front flippers like oars to move through the water.1
• Vocalization and Social Behavior: Sea lions and fur seals are highly social, congregate in large groups, and communicate with loud barks or bellows. True seals are generally less social and communicate with soft grunts.1