The Harlequin Duck is a small sea duck

Merginae

The seaducks, Merginae, form a subfamily of the duck, goose and swan family of birds, Anatidae.As the name implies, most but not all, are essentially marine outside the breeding season. Many species have developed specialized salt glands to allow them to tolerate salt water, but these have not yet...

. It takes its name from Arlecchino, Harlequin

Harlequin

Harlequin or Arlecchino in Italian, Arlequin in French, and Arlequín in Spanish is the most popularly known of the zanni or comic servant characters from the Italian Commedia dell'arte and its descendant, the Harlequinade.-Origins:...

 in French, a colourfully dressed character in Commedia dell'arte

Commedia dell'arte

Commedia dell'arte is a form of theatre characterized by masked "types" which began in Italy in the 16th century, and was responsible for the advent of the actress and improvised performances based on sketches or scenarios. The closest translation of the name is "comedy of craft"; it is shortened...

. The species name comes from the Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 word "histrio", "actor". In North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 it is also known as Lords and ladies. Other names include painted duck, totem pole duck, rock duck, glacier duck, mountain duck, white-eyed diver, squeaker and blue streak.
Adult males are slate blue with chestnut sides and white markings including a white crescent at the base of the bill.