About one in every 10,000 chickens is born gynandromorphous — that is, half-male, half-female. Chickens like this look like they're divided down the middle, with different colored plumage as well as a different muscle structure on the different sides of their body.
More about gender-bending animals:
- Chickens aren't the only ones who can be gynandromorphous; lobsters, crabs and some insects can be born this way too, though it is still rare.
- Though it's unusual to find truly half-male and half-female animals, hermaphrodism is common in the animal world. Many species of worms, snails and even fish are hermaphroditic, since they have both female and male reproductive organs, but not gynandromorphous, since they lack the characteristic "split body" look.
- Not all gynandromorphs have a clearly split body, though — some, known as mosaic gynandromorphs, look like a mixture of both sexes. This is particularly common in butterflies.