There are not only two genders as you might think.
Recently, I heard a super exciting thing: avocados change sex every day. Some avocados look cute, but in fact they are a big guy in their hearts. When they wake up in the morning, they are avocados; by noon, the flowers are closed and become male avocados; and then in the evening they bloom again to become avocados. Therefore, the avocado looks unremarkable, but in fact, the inside is really yellow and green.
Before we get started, though, let's discuss you and me. That is, we humans.
As human beings, we basically have only two genders (basically, not all of us!). ）。 Most of us either have Tintin or Big Mimi. In other words, our sex chromosomes are either XY combinations or XX combinations. Some people are more sad, with only one chromosome, or more than two chromosomes, that is, XXX, XYY or XXY. There are also a small number of people who are born with xx chromosomes, but also carry a small Y chromosome, so these people look subtly like men.
So to sum up, human gender is far more complex than most of us think (not to mention the gender identity problem that humans have always had, or more complicated). But fish, thousands of species of fish, are actually quite casual about gender, because the fish really change their personality when they're fine. Take the crescent moonfish, for example, which inhabits the Indian Ocean and the Western Pacific Ocean and is born as a female. Ten days later, according to the complex population structure, the fish all became males. Many fish maintain one sex for years, and when they mature, they become another sex.
This sex change, called sequential hermaphroditism, and sequential dichogamy if placed on plants, suggests that sex in nature is far from male or female. Many small animals are hermaphrodites, which means that they can play a role of a certain sex at any time of their ability to reproduce, as are many plants (most flowers have both stamens and pistils). The aforementioned sequentially denatured creatures are only a little more special.
Let's take a look at the avocados.
Most plants have sexual organs that grow in a single flower, so the pollen of the flower (think of as the sperm of the flower) can fall directly to the staleum (that is, the female part). The stigma catches the pollen and then begins the process by which it hatches the ovules. But for plants like the avocado, the same avocado has both male and female flowers, or simply each plant is of a single sex. But the magic of the avocado is that it only blooms flowers of one sex at a time. For example, type A avocados are female when they wake up in the morning, and B become females at noon (and vice versa).
Of course, pollinators are still able to fertilize the avocado – only the process doesn't last a few minutes, hours, but days. For avocado farmers, this is not good. Take, for example, the Haas avocado. You can see them in supermarkets, but in orchards they are grown with B-type varieties. Haas avocados are actually great, their male and female flowers are open at the same time, but on different trees. In this way, its reproductive efficiency is greatly improved, even if there are B-type varieties mixed in.
Let's talk about the clownfish.
Clownfish are probably the most famous hermaphrodite species. At birth, clownfish are only male. The reason for this is that the society of the clownfish is a matrilineal society, and the most arrogant female clownfish will only mate with one male clownfish in her lineage. When the female fish dies, a juvenile clownfish in the clan will undergo a period of change, and then transform into the female fish boss to fill this gap. Of course, most of the hermaphrodites are basically females when they are born, and the social process of fish and the society of clownfish is exactly the opposite, so from this point of view, clownfish are also a minority.
Remember Daddy Clownfish in Finding Nemo? If the actual situation is followed, the fish will change its sex to a clownfish mother at the beginning of the film. In fact, nearly 500 species of fish in the sea undergo denaturation, including groupers, bulbophyllums, and more.
But why do you have to go so hard to change back and forth? One reason is that this can significantly reduce reproductive competition between males. Imagine that the brother who was still fighting with you with the bayonet yesterday suddenly changed his personality today and called you husband, which is too exciting. But the more specific reasons are less clear to biologists. From an evolutionary perspective, transgenderism is beneficial for a species, but apparently every organism involved in the process may not necessarily feel that way.
At the end of the original text, there are other species that are denatured in the collection, and interested students can search to see.
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