This chicken has bilateral gynandromorphism — meaning, it contains both male and female characteristics.
(Michael Clinton/Roslin Institute, University of Edinburgh via The New York Times)
An image provided by Nipam Patel shows, from left, a male Pamela butterfly, a mosaic gynandromorph and a female. Split-sex animals and insects could offer clues as to why certain diseases strike one gender more often than another. (Nipam H. Patel via The New York Times)
An image provided by Nipam Patel shows, top left, a male blue morpho butterfly; top middle, a female. The remainder are gynandromorphic, with both male and female characteristics. (Nipam H. Patel via The New York Times)
Half female, half male: Unusual, but not rare : 3 / 3