Bright orange with three white bars, these distinctive fish — made famous in the movie "Finding Nemo" — are also known for their gender shifting. That’s because they’re hermaphrodites, born capable of operating reproductively as both males and females. But they’re not the familiar kind of hermaphrodite that produces eggs and sperm at the same time. Clownfish are sequential hermaphrodites, born one gender but able to switch to the other if necessary. In this case, the about-face runs from male to female (called protandry).
Here’s how it works: Clownfish live in groups where only two members are sexually mature, a large male and an even larger female. The rest are smaller, sexually immature males. If something happens to the female in the breeding pair, her male mate transforms into a female and selects the next biggest male in the group to become her new partner.