Paul Hobson / Harlequin duck (Histrionicus histrionicus) male on river Lxa, in summer plumage, Iceland June

Peter Cairns / Harlequin duck (Histrionicus histrionicus) male in rapids, Seljalandsfoss, Iceland, June

Chris Mattison / Harlequin poison dart frog (Oophaga histrionica), captive, occurs in Ecuador

Thomas Marent / Harlequin Poison Dart Frog (Dendrobates histrionicus) guayacana color morph, Colombia

Thomas Marent / Harlequin Poison Dart Frog (Dendrobates histrionicus) arusi color morph, Colombia

Thomas Marent / Harlequin Poison Dart Frog (Dendrobates histrionicus) codicia color morph, Colombia

Erlend Haarberg / Female Harlequin duck (Histrionicus histrionicus) on water, Iceland, June 2008

Erlend Haarberg / Harlequin duck (Histrionicus histrionicus) pair mating, Iceland, June

Erlend Haarberg / Male Harlequin duck (Histrionicus histrionicus) on water, Iceland, May

Steve Gettle / Harlequin Duck (Histrionicus histrionicus) male taking flight, Barnegat Light, New Jersey

Steve Gettle / Harlequin Duck (Histrionicus histrionicus) male, Barnegat Light, New Jersey

Diane McAllister / Harlequin duck (Histrionicus histrionicus) female about to dive into LeHardy Rapids. Yellowstone National Park, Wyoming, USA, May