Males and females of a species typically possess different sexual characteristics determined by their chromosomes, but sometimes, nature tosses a chromosomal curve ball. The video above explores gynandromorphism, most recently spotted in a striking northern cardinal in Illinois.
Correction, Jan. 30, 2015: A graphic in this video originally misattributed XX chromosomes to males and XY chromosomes to females. It also incorrectly suggested eggs can carry a Y chromosome. The video has been updated.