Hello dear readers! I continue a series of articles about karzubykh therefore for your studying I suggest the next informative article. But I will begin, perhaps, with a small introduction to the life of this family.
Probably everyone who took a school course in zoology knows who such amphibians are. Amphibians are the first land vertebrate animals on our planet.
But based on the name, it turns out that this group of animals mastered the land very mediocre, since their skin must be constantly moist and the process of reproduction takes place in water.
And maybe so that some animal lived in the water, and multiply out on the land? Of course, a good example is sea turtles, which lay their eggs on the seashore in sandy holes. They leave the water only once a year and only to lay eggs.
What about fish that can breed on land? It seems to be a stupid question, but there are such fish too!
It is enough to study the tropical regions of Central America and Africa, where there are many different freshwater bodies of water (ranging from puddles to lakes that dry out in a few months).
Most of the inhabitants of these bodies of water have adapted to this kind of life: small crustaceans lay eggs in the bottom mud, ciliates form ciliates, and insects simply leave this body of water and go in search of another. But what about the fish? But it’s not so easy with fish, there are fish that can crawl over the dew to other water bodies overnight, or they simply dig deep into the mud and wait for the rainy season.
In seasonal lakes such sludge will be wet until the onset of the rainy season, since its upper part is covered with a dry crust, which does not allow moisture to evaporate from the lower layers.
And what happens to the inhabitants of puddles and pools? They dry out during the drought season and turn into dust.
Such reservoirs are called ephemeral, that is, temporary, with a short life phase. But as soon as the first rain falls, the puddles are filled with water and a huge number of small and beautiful fish.
The oxygen regime in them is excellent, which allows the fish to exist there without any problems. Where then are these fish during the long months of drought?
It turns nowhere! At this time, they simply do not exist in nature. So then where does life appear in such pools?
It will sound trite, but life appears from the eggs. But then what is this caviar so that does not disappear in the dust?
This question is precisely the key secret of the inhabitants of temporary reservoirs.
The fishes inhabiting the ephemeral reservoirs are considered annuals and they live for only a few months. They are born and die in a couple of months.
However, in such a short period of time these fish have time to live a real life, from birth to the continuation of their own kind. As you already understood, ephemeral fishes live in ephemeral reservoirs.
The first generation lives for three months – then a 9-month pause, and so every year, an endless process.
But it would be quite appropriate to ask the following question: “How did these fish adapt to such long pauses?”. Not one dozen years ichthyologists spent on the study of this issue. From the first days of the study, it was found that a long 9-month period falls on caviar.
What is this caviar so unusual that it can live in sand and dust for almost a year? Moreover, not one hundred antelopes and gazelles pass through the calf every day, but she does so.
To understand this point, let’s study the life cycle of the fish themselves, perhaps it is the Notobranchus, the Afiosimeon, or other representatives of the tooth-toothed ones?
Suppose today was a heavy downpour and puddles filled with water. And after five or six hours a bunch of fry already swims in it. The speed is simply amazing, because the fish have no time to pull the rubber.
As we used to see, absolutely helpless larvae are born out of eggs, constantly hiding in the grass or under stones. As soon as the yolk sac resolves, the youngsters leave the shelter and swims swiftly around the pond. But this is a normal procedure for most species of aquarium fish.
Here the situation is somewhat different.
Fully formed fry jumps out of the wet dust, which has become the bottom of a filled puddle. And from the first days he begins to pursue all edible animals.
After some couple of months, the fry turn into healthy and strong fish. Males have a bright color, long fins and they begin to intensively care for modest females. And this is despite the fact that the male must also conquer some territory in a full puddle.
And you have to win with the same kindred. For a short period of time, skirmishes over the ownership of territories in a modest reservoir are frequent and the strongest one wins them – who has the most beautiful fins, he won.
Here nature has done everything carefully: good parents will have good offspring.
The defeated fish can only lay down its fins and leave the place of the fight in search of another opponent. Soon the winner will find a female and lead her to the conquered territory. And here begins the process of grooming the bride, where the key factors are the pomp, strength and color of the fins.
Only mating advances of males in front of females are not mating games, they are starting stimuli. Due to such behavior of the male, the female begins accelerated hormonal development, which contributes to a more rapid maturation of the eggs.
Just a couple of days of such flirting and two partners are ready to spawn. Then they are pressed by the bodies to each other and are sent to the mud. Penetration is not deep, but the eggs burrow 4-5 centimeters below the bottom of the puddle.
It is from the surface of a dry puddle that the wind will strenuously lift dust and spread it around. There can be about ten such dives in the ground, as a result of which the whole caviar is buried in the mud. That’s it, the fish fulfilled their main tasks.
Then they can only live their short lives, the fish stop eating and slowly swim in a puddle. They seem to know that their home will dry out soon and they will die. Such temporary reservoirs may dry up after a week, and after a month and a half.
But whenever this happens, the fish are doomed in any case, despite the fact that they are full of vital energy. In aquarium conditions, the toddler lives for several years.
And what happens to the caviar? Like parents, the caviar is in a hurry to live: the process of the formation of the embryo proceeds extremely quickly, the egg at this time is breathing heavily. In total there are 4 stages of embryo development.
Three of them proceed very quickly, and the fourth bang does not start at all. Why is that?
On this, scientists have found a logical explanation. In other fish in the fourth stage of development, the embryo breaks the shell and comes out.
But the larvae of the kartozubyh have nowhere to go, because there is only sand and dust around, there is no water.
And how then do they know when it is time for them to be born? It turns out that the chemical parameters of water in the pool towards the end of its existence are a kind of activator for a long pause for the development of caviar.
These properties are significantly different from those that have fresh rainwater, which filled the puddle. Therefore, the egg waits when fresh rainwater appears around it again. The newly filled puddle is a signaling device for the resurrection of conserved embryos.
While the egg waits for the influx of fresh rainwater, all the processes of vital activity are severely slowed down. But since the onset of rainwater, these processes are sharply activated and proceed very quickly.
But the most surprising thing about this is not the long pause of annual fish, but the egg itself. Eggs of the karbozubyh has a particularly durable shell structure.
During experimental trials, the egg held a load of 500 grams. An elephant cannot crush such an egg, and a bird from sand and dust simply will not reach.
And the fact is that the outer layer of caviar is covered with a special adhesive substance, which adheres to sand, lint, lumps of soil. As a result, the poor egg becomes a grain of sand.
But we have not reached the most interesting. When the dry period comes, the outer shell of the egg stratifies and a sealed ball appears between the outer and inner shells. Inside it is a liquid medium, where the germ and is experiencing a period of drought.
But now it is difficult to call such a construction an egg? The fact is that such a structure with a solid shell is not peculiar to fish, but to eggs of land insects and snakes.
In fact, annual fish are on the evolutionary ladder just below amphibians, but they are miraculously capable of laying eggs that are not inferior in complexity to the structure of a lizard egg. Well, how not amphibians vice versa?
These are interesting teeth!