How does the marine otter differ from the sea otter?

While both the sea otter (Enhydra lutris) and the marine otter (Lontra felina) are marine-dwelling mammals, they differ significantly in their biology, behavior, and classification.12

Key Differences

• Classification: The sea otter is a distinct species and the only member of its genus. The marine otter is a member of the genus Lontra, which primarily consists of freshwater river otters that have adapted to marine environments.132
• Size: Sea otters are much larger, weighing 16–40 kg (35–90 pounds). Marine otters are significantly smaller, typically weighing only 3–6 kg (6.6–13.2 pounds).12
• Habitat and Range: Sea otters inhabit the northern Pacific, often ranging far offshore and gathering in large "rafts". Marine otters are found along the rocky Pacific coast of South America (Peru, Chile, and Argentina) and stay within 100–150 meters of the shore.12
• Behavior: Sea otters are highly adapted to life at sea, often sleeping and eating while floating on their backs. In contrast, marine otters spend much more time on land, utilizing sea caves and rock crevices for resting, breeding, and raising their young.132