Did you know that many of the lovely fish we regularly see on the coral reef have the ability to change their sex? The biological term is ‘sequential hermaphroditism,’ and wrasses, moray eels, gobies and clownfish are known to do this.
According to Wikipedia
“A school of clownfish is always built into a hierarchy with a female fish at the top. When she dies, the most dominant male changes sex and takes her place. In the wrasses (the family Labridae), sex change is from female to male, with the largest female of the harem changing into a male and taking over the harem upon the disappearance of the previous dominant male.”