Seals & Sea Lions

Seals and sea lions belong to a group of marine mammals called pinnipeds, which means fin or flipper-footed. These animals live in the ocean, but are able to come on land for long periods of time. Some species have evolved the ability to hold their breath for up to two hours and dive to depths of more than 6,500 feet when looking for food.

There are two families of pinnipeds: Phocids and Otariids. Phocids are also known as earless seals or “true” seals. They have ear holes, but no external ear flaps. They also have small front flippers and move on land by flopping along on their bellies. At sea, these seals move their rear flippers back and forth like a fish's tail to propel themselves through the water. Phocids include the harbor seal and Hawaiian monk seal.

Otariids, also known as eared seals, include sea lions and fur seals such as the Steller sea lion and the northern fur seal. Unlike true seals, they have external ear flaps. Their front flippers are large, and on land, they are able to bring all four flippers underneath their bodies and walk on them. Otariids propel themselves in the water by paddling their front flippers and using their rear flippers to steer. 

All seals and sea lions are protected under the Marine Mammal Protection Act, and some are also listed under the Endangered Species Act. Together with our partners, we work to study, protect, and conserve these unique marine mammals and their habitats.


Species News

Hawaiian monk seal and her pup snuggling on each others neck in the waters by the rocks. R006 relaxes with one of her many pups at Kalaupapa, Molokaʻi. Credit: NOAA Fisheries
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 “eared 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.
Black Hawaiian monk seal pup lies on its back, wide-eyed, on a sandy shore and looks into the camera. Hawaiian monk seal pup taking it easy on a beach in the Northwestern Hawaiian Islands. Credit: NOAA Fisheries Hawaiian Monk Seal Research Program

Multimedia

Pair of bottlenose dolphins Pair of bottlenose dolphins. Credit: NOAA Pacific Islands Fisheries Science Center/Lisa Morse.
A Hawaiian monk seal rests on the beach at the edge of the waves with a small, darker pup by her side. Female Hawaiian monk seal RO28, one of the “monk seal matriarchs,” and her pup on Kaua‘i. Credit: Val Bloy

Research

Peer-Reviewed Research

Publications by Northeast Passive Acoustic Research Staff

Our staff regularly publish their findings in scientific journals and Center-produced documents…

Passive Acoustic Research in the Atlantic Ocean

Marine mammals and many fish produce and receive sound in the ocean. In an environment where vision is limited, hearing is one of the most important senses. These animals rely on sound for navigating, socializing, establishing dominance, attracting…

Protected Species Gear Research

We work closely with the commercial fishing industry to reduce harmful interactions with marine mammals, turtles, and other protected species.

Developing Viable On-Demand Gear Systems

On-demand gear development continues to evolve with the help of industry.

Viewing Marine Life

Watching marine animals in their natural habitat can be a positive way to promote conservation and respect for animals and their environment.

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Species

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