Seals and Sea Lions: Marine Mammals with Flippered Feet

Seals and sea lions are members of a group of ocean-dwelling mammals known as pinnipeds, a name that means “fin-footed” or “flipper-footed.” These animals spend much of their lives in the sea but are also capable of staying on land for extended periods.

Many pinniped species have developed remarkable diving abilities. Some can remain underwater for nearly two hours and descend to depths exceeding 6,500 feet while searching for prey.

Two Main Families of Pinnipeds

Pinnipeds are divided into two primary groups: Phocids and Otariids. Although both groups are adapted for life in the ocean, they differ in their body structure, movement, and physical features.

Phocids: The True or Earless Seals

Phocids are commonly called true seals or earless seals. They do have ear openings, but they lack visible external ear flaps.

These seals have relatively small front flippers and move on land by sliding and pushing themselves forward on their bellies. Their movement on shore is less efficient compared with sea lions.

In the water, phocids use their powerful rear flippers in a side-to-side motion similar to the movement of a fish’s tail, allowing them to swim efficiently through the ocean.

Examples of phocids include harbor seals and Hawaiian monk seals.

Otariids: Sea Lions and Fur Seals

Otariids are known as eared seals and include sea lions and fur seals, such as Steller sea lions and northern fur seals.

Unlike true seals, otariids have visible external ear flaps. They also possess larger front flippers, which provide powerful movement both in the water and on land.

When on shore, these animals can rotate their rear flippers beneath their bodies, allowing them to stand up and walk using all four flippers.

While swimming, otariids mainly rely on their strong front flippers to move forward and use their back flippers for steering and direction control.