An unusual male – female relationship exists among the brightly colored cleaner wrasse,

Labroides dimidiatus of Australia’s Great Barrier Reef.

The pugnacious 4 inches long fish defends its territory and his harem of up to 16 females.

In addition to patrolling he must keep his females in line.

One of these females usually dominates the others.

The male is very aggressive to her – since

she threatens to assume his role and even his gender.

Only hours after the death of the male the dominant female takes on his role.

She presides over the harem and assumes distinct male behavior.

Within a month she becomes a fully functional male.

The next dominant female will become the male after this female-turned-male.