While most species of moray eels are born either female or male and remain that way for life, a few are sequential hermaphrodites. For example, ribbon morays, like the one pictured here, switch from male to female. Unlike clownfish, though, all of them make the switch. That is, every ribbon moray is born male and later becomes female via a remarkable (and colorful) process. Young males start out small and black with yellow dorsal fins. As they mature and begin fertilizing eggs, they gradually turn blue with yellow faces. However, once they grow a little bigger, male ribbon morays become yellow or greenish-yellow and develop female reproductive organs, living out the rest of their lives as egg-laying females.
Zebra and dragon moray eels, on the other hand, switch genders in the opposite direction from female to male (called protogyny). This usually occurs when males are in short supply.