Gender change can still cause a lot of discussion among people.
In nature, however, it is a natural process
not uncommon on coral reefs.
In this episode you will meet a fish that is probably known to every child.
But from a slightly different side.
Sex is established relatively early in most vertebrates
and it doesn't change anymore.
However, some bony fish
they can surprise us.
Why?
Because they have the ability to change sex
in adulthood under the influence of environmental factors.
A species of fish that is an iconic example of sex change
is your favorite, in the world of children known as "Nemo".
i.e. clownfish.
Notice that little Nemo is a boy.
This has some justification in reality.
In clownfish, we can observe the phenomenon of the so-called protandry.
This is the earlier maturation of the male gonads.
In short, this means that our clownfish mature as "boys".
Clownfish are monogamous fish.
They have one partner.
They can live in pairs or groups.
There is a hierarchy in this group.
The largest individual is the female,
accompanied by a mature male
and young males.
But what happens if our female gets lost somewhere?
The dominant male "breeder" changes sex
and takes the place of the female.
And the dominant "male" matures, becomes a "breeding" male.
Such a system of offspring production and the social structure of clownfish
is largely dependent on the presence of sea anemones in their environment.
Some sea anemones can reach enormous sizes.
They are the home of our clownfish,
where they can find shelter from predators, lay their eggs in a safe place and get food.
However, sea anemones on coral reefs can be distributed in a variety of ways.
Some are relatively far apart.
This means that for our clownfish, changing the host may carry a deadly risk.
So a gender reassignment strategy protects them from taking that risk.
However, this reproductive strategy requires a lot of time and energy.
Sex change in such a clownfish can take a long time, and during this time they do not reproduce.
So it's kind of a waste of time.
Interestingly, in places where we have more sea anemones, such hierarchical ties are more loose.
It is a safe environment and males migrate more often in search of a new partner.
If we were to define the "social system" chosen by clownfish, it is naturally "matriarchy",
where women are in power.
The female, being bigger, stronger, more aggressive, patrols her territory.
“The woman beats me...”
In contrast, all males in the group care for the offspring,
thus contributing to the reproductive success of the main pair.
In the Gdynia Aquarium we breed three species of clownfish.
The simplest in breeding is naturally our clownfish.
The older the pair of clownfish, the more eggs they can lay.
Spawn in breeding tanks is laid by a couple more or less every month.
Such pairs can lay 100-200 eggs at a time.
They lay their eggs on hard surfaces. Aquarists use, for example, pots or - as in our case - PVC pipes.
After 8-9 days, small larvae hatch from the eggs.
This usually happens at night.
The young are placed in a dense plankton suspension
composed of small plant and animal organisms,
so that they have enough food.
After a week, they develop an appetite for small crustaceans.
After 3 months, they are already about 3-4 cm long.
So you see - our clownfish can surprise.
I hope that after this episode, coral reefs will be an example of a wonderful, colorful ecosystem for you,
where the rules of life can change,
sometimes contrary to our expectations.