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. Seven seals and sea lions are also listed as threatened or endangered in part of their range under the Endangered Species Act:
- Bearded seal
- Guadalupe fur seal
- Hawaiian monk seal
- Mediterranean monk seal
- Ringed seal
- Spotted seal
- Steller sea lion
Together with our partners, we work to study, protect, and conserve these unique marine mammals and their habitats.
Species News
“Pearl” the gray seal pup in rehabilitation at the Mystic Aquarium Animal Rescue Clinic, after stranding in Charlestown, Rhode Island, in January 2025. Credit: Mystic Aquarium.
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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. Credit: iStock
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Watching Wildlife: How to Share the Shore and Sea with Marine Animals
Alaska
New England/Mid-Atlantic
Pacific Islands
Southeast
West Coast
National
Gray seal, Louis Armstrong, is released at Assateague Island National Seashore following rehabilitation at National Aquarium in Baltimore, Maryland. Credit: National Aquarium
Feature Story
NOAA Fisheries Awards $3.8 Million for Marine Mammal Rescue Efforts through Prescott Marine Mammal Rescue Assistance Grants
Alaska
New England/Mid-Atlantic
Pacific Islands
Southeast
West Coast
National
Credit: National Park Service/Glauco Puig-Santana (NOAA Fisheries Permit #22677)
Multimedia
Photo Gallery
Papahānaumokuākea: 2025 Monk Seal and Sea Turtle Field Season Highlights
Pacific Islands
Cape Shirreff field camp on Livingston Island, one of the most breathtaking places in Antarctica. Credit: NOAA Fisheries
Research
Innovative Technologies Expand Research Capabilities in Alaska Marine Ecosystems
We are working to better understand Alaska ocean ecosystems and to gather information to ensure healthy fish, crab, and marine mammal populations. We use innovative technologies to both monitor and study marine life and habitat.
Surveys in the Northeast and Mid-Atlantic
We conduct research and monitoring surveys to better understand the physical, biological, economic, and social components of marine ecosystems found in the Northwest Atlantic Ocean from the Canadian Scotian Shelf to Cape Hatteras, North Carolina.
On-Demand Gear Guide
A roadmap for providing fishermen an option to use on-demand fishing systems in the Greater Atlantic Region by 2028.
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.
