Women of 500 fish species can quickly turn into men. How and why do they do that?

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Virtually all of us are convinced that the gender of every living organism is determined in the course of development in the womb and lasts a lifetime. In nature, however, there are about 500 species of fish that can change their gender if necessary and turn from women to men and vice versa. How and why they do it is still a mystery to scientists, but a group of New Zealand researchers finally answered that question. They explained this process using the example of fish called blue-eyed talasoma living in the Caribbean Sea.

These tropical fish live in groups where there are several females and only one male. The male is distinguished from them by the blue color of the head and is mainly concerned with foraging and protecting females from predators. Such a lifestyle is very dangerous, so men are often lost or dying, and one of the women has to become a man and put her friends under her protection.

Why do fish change their gender?

A sex change takes place in record time – within a few minutes, the woman gains a courageous character, and the color of her head changes in a few hours. Their ovaries, in which the female reproductive cells are formed, the eggs, turn into male testicles in just 10 days and begin to produce sperm.

Blue-eyed Thalasome: Blue male and yellow female

Scientists have long been unable to explain exactly how this process works, but now the mystery is finally revealed. The researchers performed an experiment in which they independently removed males from several fish groups, forcing the females to change their gender. During this process, the scientists carefully monitored all changes in the organisms of the fish.

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They believe that the females experience great stress after the disappearance of the male, causing the cells of the female reproductive organs to die quickly. At the same time male cells begin to produce in their organisms, from which later male organs arise. During all of these women's processes, the look and character begin to change.

What kind of fish can change the soil?

According to the researchers, the same processes take place in organisms and other amazing fish that can change their gender. The best known representatives of such species are clown fish, but in their groups the sex change is exactly the opposite. The fact is that most of them are born men and the main fish in the group are big women. When the main female dies, one of the males changes sex to the female.


After the publication of the research results, scientists appeared who disagreed with them. For example, Professor Matthew Grober of Georgia State University asked why fish do not change their gender when they are under stress every day. In his opinion, scientists from New Zealand have clearly overlooked something, and the process of gender reassignment is currently beginning for another, unknown reason.

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