Sea Otters

Sea Otters

Why in the news?                        

A recovering population of sea otters in California, especially in the Elkhorn Slough National Estuarine Research Reserve, has helped curb green crab proliferation.

About Sea Otter:

• This aquatic member of the weasel family is found along the coasts of the Pacific Ocean in North America and Asia.
• It spends most of its time in the water but, in some locations, comes ashore to sleep or rest.
• Sea otters were extensively hunted in the 18th and 19th centuries for their thick, soft fur.
• Their numbers rebounded after being listed as threatened and federally protected in 1977.
• Sea otters consume 50,000 to 120,000 green crabs annually, effectively controlling their population. This marks a significant solution to the invasive species problem on the West Coast of the United States.
• Unlike other marine mammals, sea otters rely on a high metabolism rather than blubber to stay warm in cold oceans. They consume about 25% of their body weight daily, making them voracious predators.
• Sea otters have webbed feet, water-repellent fur to keep them dry and warm, and nostrils and ears that close in the water.

Green Crab (Portunus Sanguinolentus):

• The green crab is a common littoral crab, recognized globally by names such as shore crab or green shore crab in the British Isles. It is one of the top 100 “world's worst alien invasive species”, showcasing its invasive nature.
• Habitat: Native to the Atlantic Ocean and Baltic Sea, but now spread to Australia, South America, and South Africa.

Physical Features:

○At maturity, the carapace width measures about 90 mm.

○Colouration varies between green, brown, grey, and red, with delayed moulting causing red colouration.

• Diet: Feeds on small crustaceans, molluscs, and worms.
• Impact on Ecosystems: The green crab’s invasive behaviour harms coastal ecosystems by:

○Damaging seagrass beds, critical habitats for various marine species.

○Overhunting prey species, crucial for the survival of other native species.

○Outcompeting native species for resources like food and habitat.

                                                              Source: Indian Express