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Credit: Nathan Brockman, Reiman Gardens
Some creatures can't pick sides, like this half-male, half-female leopard lacewing butterfly. Dual-sex animals like this one, called gynandromorphs, are also found in birds and crustaceans. This butterfly emerged from its chrysalis at Iowa State University's Reiman Gardens in 2008. Half of its body is male, with a male's orange, black and white wing. The other half is female, with a female's paler wing.