Clown fish start life as males and live inside a sea anemone, together with a female clownfish. The female prevents the males from changing sex by bullying them. When she dies, the largest male changes sex and takes over her role.

Wrasses, damselfish and antheas, not only change sex, but also colour! Unlike clownfish they are born females and later change into males.

Usually there is one male in charge of a harem of females. When he dies the largest female changes colour and becomes a male within a matter of days.

What an interesting concept…