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Is It a Seal or a Sea Lion?

August 12, 2024

Seals and sea lions are both pinnipeds, but they have distinct characteristics that set them apart. Learn how to recognize a seal vs. a sea lion.

Infographic showing illustrated seal and sea lion and describing the differences between the two animals, such as ears, body size, flippers, etc. At first glance, seals (true or “earless seals”) and sea lions look fairly similar. Taking a closer look, these are some of the general differences to tell these animals, such as on the harbor seal (left) and California sea lion (right) pictured above.

Seals and sea lions, along with walruses, belong to a group of marine mammals called “pinnipeds.” Pinniped means fin or flipper-footed in Latin. These animals spend the majority of their time in the ocean but come on shore for long periods of time. 

Although seals and sea lions are similar, they are not the same. There are several physical characteristics and adaptations that you can look for to tell the difference between seals and sea lions.

How to Recognize a Seal

“True” seals, also known as “earless” seals or simply “seals,” belong to a group of pinnipeds that have ear holes but lack an external ear flap. This includes species such as the harbor seal, endangered Hawaiian monk seal, and harp seal.

Seals typically have a smaller body size compared to sea lions. But some, such as the Northern elephant seal and hooded seal, can be larger.

On land, seals use their bellies to move around in a caterpillar-like motion. They have small front flippers that are thinly webbed with a claw on each small toe. In the water, seals swim easily, moving their rear flippers back and forth, similar to how a fish uses its caudal fin (tail) to propel itself through the water.

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A Hawaiian monk seal swims in blue-green water near a gray rocky cliff
Seals use their rear flippers to propel themselves forward underwater. They use their front flippers to steer. Credit: NOAA Fisheries (Permit #22677).

In general, seals are quiet. When they vocalize, it’s with soft grunts, growls, or hisses. Many are less social than sea lion species, especially in the water, but seals can be found on land together to avoid predators, rest, mate, and nurse their pups.

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A Hawaiian monk seal lays on its side on the beach with the ocean in the background.
Hawaiian monk seals and other “true” seals have small front flippers and ear holes but no external ear flap. Credit: Mark Sullivan.

How to Recongize a Sea Lion

Sea lions, such as the California sea lion and Steller sea lion, belong to a group of pinnipeds that have external ear flaps—giving them the nickname “eared seals.” This group also includes fur seals like the threatened Guadalupe fur seal.

On land, sea lions use their large, elongated front flippers and rear flippers rotated underneath their bodies to “walk.” In the water, they propel themselves by paddling their front flippers and use their rear flippers to help steer, like a boat’s rudder.

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california-sea-lions.jpg
Sea lions “walk” on land by rotating their hind flippers under their bodies. Credit: NOAA Fisheries.

Sea lions can be noisy and are easily recognizable by their loud and distinct “bark.” They commonly congregate in large groups called “herds” or “rafts.” They can be seen together on offshore rocks, sandy beaches, and sometimes human-made structures such as jetties and piers.

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Group of tan and brown California sea lions stand together on a beach.
Eared seals like the California sea lion get their name from their external ear flaps. Credit: NOAA Fisheries/Tony Orr.

All seals and sea lions are protected under the Marine Mammal Protection Act and some are also listed under the Endangered Species Act. It is important to view these wild animals from a safe and respectful distance for their safety—and yours. If you see a sick or injured seal or sea lion, please call your nearest marine mammal rescue organization.

Last updated by Office of Communications on December 10, 2024