An animal that can change their sex?!

[Juan]

I saw this short:

And the information caught me off guard that when the dominant male Parrotfish of the group disappears, the biggest female switches to a male so the ecosystem can continue?! 

Maybe some of you guys already know this but this is mind bending to me, I didn’t know such thing could happen.

[Leo Gura]

There are more examples that just that.

Other animals can do that.