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

Lethargic subadult male Steller sea lion in the Kodiak harbor entangled in a plastic packing band. Lethargic subadult male Steller sea lion in the Kodiak harbor entangled in a plastic packing band. Credit: Sun'aq Tribe of Kodiak/Matt Van Daele, NOAA permit No. 24359.
An injured gray seal lying on the beach. Gray seal. Credit: MERR Institute
A rainbow-shaped wave of water ebbs away into an arc around a  Hawaiian monk seal mom laying on a sandy beach as her newborn pup  lays next to her resting its head on its mom. Hawaiian monk seal RK96 (Kaiwi) and her newborn pup at Kaimana Beach, Waikīkī. Credit: NOAA Fisheries (Permit #24359)
Two stranding responders carry a stranded harbor porpoise away from some rocks A harbor porpoise is retrieved from the rocks at Odiorne Point State Park, New Hampshire. Credit: Seacoast Science Center


Cape Shirreff field camp against a backdrop of mountains in Antarctica. Credit: NOAA Fisheries Cape Shirreff field camp on Livingston Island, one of the most breathtaking places in Antarctica. Credit: NOAA Fisheries
A Hawaiian monk seal pup lays in the sand A young, female Hawaiian monk seal pup, identified as "PM6," lying in the sand at Kalaupapa, Molokai in 2017. This is the fourth pup of mom "RI25." Credit: NOAA/Tracy Mercer (Permit #16632-02).


Peer-Reviewed Research

Understanding Perceptions That Drive Conflict Over the Endangered Hawaiian Monk Seal

The importance of resource managers articulating their own assumptions and values, and to work to…

Hawaiian Monk Seal Updates 2023

2023 monk seal updates from NOAA Fisheries in the Pacific Islands.

Marine Mammal Acoustics

We record the sounds produced by marine mammals and study their behaviors, locations, population sizes, and potential threats.

Toxoplasmosis and Its Effects on Hawaiʻi Marine Wildlife

NOAA is responsible for managing endangered species, including the Hawaiian monk seal. One of the greatest population threats is the infectious disease toxoplasmosis, a threat many people haven't heard about. Learn how you can help protect Hawaiian monk…

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.

On Shipwreck Beach on the south coast of Kauai, Hawaii, an endangered Hawaiian monk seal takes a nap on the beach. The sign in the foreground instructs people to walk around the seal.