Duque, a Baleia whale, appears in the 1975 Japanese anime adaptation of Hans Christian Andersen's fairy tale. He acts as a messenger for the Sea Witch, delivering her warnings about impending storms to marine life in the undersea kingdom. His role involves alerting creatures to seek shelter before the Sea Witch generates destructive weather conditions endangering ships and ocean inhabitants. Duque interacts with Fritz, an Atlantic dolphin calf who is Princess Marina's closest companion. When Marina faces mortal peril after her transformation into a human and the prince's marriage to another, Fritz desperately searches to save her from dissolving into sea foam at dawn and seeks Duque's assistance. This plea connects Duque to the Sea Witch's sphere of influence; his specific actions during this event are not detailed beyond facilitating communication or access to the witch. The whale's relationship with the Sea Witch positions him within the hierarchy of the ocean's mystical beings, functioning as an intermediary for her powers. His actions primarily revolve around storm warnings and tangentially connect him to the central characters' fates during moments of crisis.