Quick answer
The sea otter is a marine mammal of the North Pacific coast and the smallest marine mammal, famous for floating on its back, using rocks as tools to crack open shellfish, and holding hands while resting. It has the densest fur of any animal, with up to a million hairs per square inch, and is a keystone species that keeps kelp forests healthy. Sea otters typically live 10 to 20 years.
Key takeaway
The sea otter is a marine mammal of the North Pacific coast and the smallest marine mammal, famous for floating on its back, using rocks as tools to crack open shellfish, and holding hands while resting. It has the densest fur of any animal, with up to a million hairs per square inch, and is a keystone species that keeps kelp forests healthy. Sea otters typically live 10 to 20 years.
Overview
The sea otter is a marine mammal of the North Pacific coast and the smallest marine mammal, famous for floating on its back, using rocks as tools to crack open shellfish, and holding hands while resting. It has the densest fur of any animal, with up to a million hairs per square inch, and is a keystone species that keeps kelp forests healthy. Sea otters typically live 10 to 20 years.
Biology
Sea Otter (Enhydra lutris) is classified as Mammal with conservation status Endangered. Typical weight 14–45 kg (31–99 lb); lifespan around 10–20 years.
Ecology
Diet: Carnivore. Habitat: Coastal North Pacific and kelp forests. Movement and social systems reflect those pressures.
People and this species
Learn before you travel or keep related pets. Wild individuals are not toys; captive care needs species-specific husbandry.
Further reading
See the full Sea Otter profile for FAQs, taxonomy, and related guides on this site.
The warmest coat in nature
Unlike whales and seals, sea otters have no insulating blubber. Instead they rely on the densest fur of any animal, with up to a million hairs per square inch, trapping a layer of air to stay warm in cold seas. They spend hours grooming to keep this fur clean and waterproof.
Tool users
Sea otters are one of the few animals that use tools. They often carry a favorite rock in a loose pouch of skin under the forearm and use it to smash open hard-shelled prey such as clams, mussels, and sea urchins while floating on their backs.
Keystone of the kelp forest
By eating sea urchins, otters stop the urchins from overgrazing and destroying kelp forests. Healthy kelp forests shelter countless other species and absorb carbon, which makes the sea otter a keystone species whose presence shapes the whole ecosystem. Otters also hold hands or wrap themselves in kelp to avoid drifting apart while they sleep.
Conservation
Hunted almost to extinction for their fur in the 1700s and 1800s, sea otters have made a partial recovery but remain Endangered. Oil spills, entanglement in fishing gear, and pollution still threaten them, and their loss can trigger the collapse of entire kelp ecosystems.
Research notes
Figures for sea otters (Enhydra lutris) come from field studies, museum records, and conservation assessments that do not always agree on exact averages. Prefer ranges over single-point claims, and check whether a source describes wild, captive, or mixed populations.
Practical takeaways
If you encounter sea otters in the wild, prioritise distance and local guidance. If you care for related domestic or captive animals, match diet and housing to species needs rather than generic pet advice. Share accurate status information (Endangered) when discussing conservation.
Sources
FAQs
Sea Otter: Key Facts & Natural History?
The sea otter is a marine mammal of the North Pacific coast and the smallest marine mammal, famous for floating on its back, using rocks as tools to crack open shellfish, and holding hands while resting. It has the densest fur of any animal, with up to a million hairs per square inch, and is a keystone species that keeps kelp forests healthy. Sea otters typically live 10 to 20 years.
What is the scientific name of the sea otter?
Enhydra lutris
What do sea otters eat?
Carnivore
Where do sea otters live?
Coastal North Pacific and kelp forests
Are sea otters endangered?
Listed here as Endangered. Check IUCN and national lists for the latest assessment.