On its left, the butterfly’s wings glisten like polished black leather. On its right, they flash colorfully, edged with leopard-gold spots, slashes of mottled silver and a bright red teardrop. The striking asymmetry is extremely rare in butterflies, not only for its beauty but for its cause. Genetically, this mismatched creature is both male and female.
Recently hatched in London’s Natural History Museum, the butterfly is technically classified as a gynandromorph. The BBC reports that its unique traits are caused by a failure of the butterfly’s sex chromosomes to separate during fertilization. Only .01% of hatched butterflies are gynandromorphs.
The genetic condition has been noted in other species, including crabs, lobsters, spiders and chickens. According to the BBC, experts believe gynandromorphy occurs throughout nature but can be difficult to observe in species where sexual dimorphism, or visual and behavioral differences between males and females, is less pronounced.
“It is a complete split; part-male, part-female… welded together inside,” Luke Brown, a butterfly enthusiast who works with the Natural History Museum, told the BBC.
This gynandromorph butterfly, a species native to Asia called the Great Mormon (Papilio memnon), gets its darker wings from its male side, while the brighter, bolder set come from its female traits. The creature also has male and female sex organs, which means it is infertile, and even its antenna are different lengths. Brown, who has hatched over 300,000 butterflies, has only seen two others like it.
“I was bouncing off of the walls when I learned [about it],” Brown said. He reported to The Guardian that the butterfly was feeding and flying well. At three and a half weeks old, it is already considered middle-aged. After the butterfly dies, the Natural History Museum will preserve it as part of its rare butterfly collection.
“The gynandromorph butterfly is a fascinating scientific phenomenon, and is the product of complex evolutionary processes,” Blanca Huertas, the museum’s butterfly curator, told The Guardian. “It is fantastic to have discovered one hatching on museum grounds, particularly as they are so rare.”
Image credit: Miranda P.