Bilateral gynandromorphs – animals that are quite literally, half male and half female.
“This condition is rare, but not unique. It’s been spotted in birds, insects and crustaceans all around the world. It’s unheard of in humans and it’s thought that it occurs differently in each of the groups listed above.
In insects the mechanism is fairly well understood. A fly with XX chromosomes will be a female. However, an embryo that loses a Y chromosome still develops into what looks like an adult male, although it will be sterile. It’s thought that bilateral gynandromorphism occurs when two sperm enter an egg. One of those sperm fuses with the nucleus of the egg and a female insect develops. The other sperm develops without another set of chromosomes within the same egg. Both a male and a female insect develop within the same body.
Ggynandromorphism doesn’t always look so perfect. Sometimes animals can possess a strange patchwork of different cells all across their bodies – it can even occur within a single feather. But sometimes, like in the butterfly above, bilateral gynandromorphism occurs and you see this perfect division between the two halves of the body.”
by Elise Andrew
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