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

Two monk seals resting near rock walls on a on public beach. Endangered Hawaiian monk seal RK96 and her pup Lōliʻi rest near a rock wall at Kaimana Beach in Waikīkī. NOAA plans to relocate the pup after weaning, in the interest of safety and to allow him to grow up as a wild seal with less human interaction. Credit: Hawaii Marine Animal Response.
False killer whale catching fish above water. A member of the false killer whale main Hawaiian Islands insular population catches a mahimahi. Credit: Cascadia Research/Robin W. Baird.
Adult monk seal and newborn pup on a public beach. RK96 and her pup resting and sleeping. Credit: Hawaii Marine Animal Response.


Peer-Reviewed Research

Sighting Patterns Reveal Unobserved Pupping Events To Revise Reproductive Rate Estimates for Hawaiian Monk Seals in the Main Hawaiian Islands

We used sighting reports to describe female breeding biology and reproductive success in the main…

SWFSC Stranding Collections

What we collect and how tissues are used 

Cetacean Life History

Stranding data fill in critical missing parts of the cetacean life history story

SWFSC Stranding Investigations

Investigating why marine mammals strand 


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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