Sea Otters

Sea otters are restoring California’s coastal ecosystems by consuming thousands of invasive green crabs annually at Elkhorn Slough National Estuarine Research Reserve, effectively tackling a persistent ecological challenge.

About Sea Otters (Enhydra lutris)

• Taxonomy: Aquatic mammal of the weasel family.
• Habitat: Found along the Pacific Ocean coasts, especially in North America (from Alaska to California) and parts of Asia (Russia and Japan).
• Behavior: Spend most of their time in the water but occasionally rest onshore.
• Physical Characteristics: Have webbed feet, water-repellent fur, and nostrils/ears that close in water.
  • Unlike most marine mammals, they lack blubber and depend on consuming large amounts of food to avoid hypothermia.

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• Diet: Carnivorous, feeding on sea urchins, crabs, mollusks, clams, and fish.
• Ecological Role: Act as keystone species in kelp forests by controlling populations of green crabs, sea urchins, and other species harmful to kelp ecosystems. 
• Climate Significance: Healthy kelp forests maintained by sea otters absorb substantial amounts of carbon, reducing ocean acidification and protecting marine biodiversity.
• Sub species of sea otter:

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Note: All three sea otter subspecies are classified as Endangered by the IUCN

Sea Otters’ Role in Controlling Green Crabs

• Predatory Impact: Sea otters consume between 50,000 and 120,000 green crabs annually.
• Unique Metabolism: Described as “super voracious predators,” sea otters rely on a rapid metabolism to stay warm, consuming about 25% of their body weight daily.
• Ecological Contribution: Their predation has significantly curtailed the green crab population, helping to restore balance and protect coastal ecosystems.