I personally feel that this is the eel in order to reproduce their own offspring from female to male, the eel is not a hermaphroditic animal, the newborn eel sex are female, so in the early eel, their main job is responsible for spawning, but if all the eels are only female eels, there is no male eels, the eel's survival as well as reproduction is quite unfavorable. So the eels will start to change into males after spawning in the later stage.

In fact, in addition to eels, there are many animals in the natural world will occur in the phenomenon of sex reversal, these animals in their own lives in a certain period of time for a certain sex, when they meet certain conditions, the body of the sex will begin to change, the performance of the sex with the opposite, such as in the sea life of red snappers, red snappers, red snappers, a family will have only one male snapper. When the original one male snapper dies, a female snapper in the family will become male.

There are also some anemone fish that have the ability to sexually reverse this ability, this kind of fish family with the red snapper above the situation is a little bit opposite, the anemone fish in the big family only a female fish, the other fish are either males, or immature, only when the only female fish died, the largest male fish in the group will become the next female fish, of course, in addition to just introduced these fish, there are many fish also have this characteristic, but also the female snapper, the female snapper, the female snapper, the female snapper, the female snapper, the female snapper, the female snapper. Of course, besides these fish just introduced, there are many other fish that also have this characteristic, so I won't introduce them all here.

I think these fish are born with this ability to sexually reverse their behavior because they need to survive, and the world is full of beautiful species and strange natural phenomena, all waiting for us to explore and discover together.