The Eider duck is a large sea duck known for its distinctive appearance and soft down feathers. Males are characterized by their striking black and white plumage, while females are mottled brown for camouflage. They primarily inhabit coastal regions in the Northern Hemisphere, often found in Arctic and subarctic areas. Eider ducks are known for their unique nesting behavior, where females line their nests with down feathers plucked from their own bodies. This down is highly prized for its insulating properties and is often harvested for use in luxury bedding and clothing. Eiders primarily feed on mollusks and crustaceans found in marine environments.