Silver carp: humiliates male fish to destroy a pond (6 photos)

Each invasive species expands its territory in its own way. Some adapt to new conditions, others squeeze out competitors. And crucian carp are especially brutal – they steal fish... their sperm!





Their invasion begins with a single fish entering the reservoir. Perhaps it was carried there by meltwater streams, or perhaps a bird accidentally carried an egg on its feet – it doesn't really matter. What really matters is that the fish is a female.



And sometimes, transporting crucian carp to a new body of water happens like this...

The thing is, female crucian carp are rather... frivolous when it comes to reproduction. She doesn't set any boundaries or conditions for herself, even within the species. Has another crucian carp come to fertilize the eggs? - Excellent. And if not, then a golden crucian carp, bream, carp, or roach will definitely arrive – a hospitable female will welcome any guest.





Do you see the difference between the fish? But the female crucian carp doesn't...

After fertilizing the clutch, the male of the other species will leave the female with a sense of fulfillment. He will never know he was trapped and will not be able to reproduce this year. After all, all the fry born from the eggs will be purebred crucian carp. And what's more, they will be complete clones of their mother.



Now we know the name of the oldest profession – crucian carp!

After all, crucian carp are unique fish that have mastered reproduction through parthenogenesis. Their eggs are capable of developing into fully fledged adults without fertilization by males – the eggs themselves complete the second half of the genetic code that would otherwise be delivered by sperm. This method has only one drawback: the eggs produce only females, and the species' adaptability is reduced.



The closest relative of the crucian carp is, oddly enough, the goldfish. Their evolutionary paths diverged only 800,000 years ago, but it cannot reproduce by parthenogenesis. However, their males are easily seduced by female crucian carp.

But for all this genetic magic to work, the egg needs a good kick, literally. Chromosome doubling only begins if a sperm pushes against the egg, but it doesn't penetrate and ensure fertilization. And sperm from other species are perfectly suitable for this.



Thanks to their sperm-stealing technology (and human assistance), crucian carp have spread widely. Just a few centuries ago, their range was limited to the Amur River and a few regions of China!

All this has a very negative impact on the population of these other species. After all, a deceived male will no longer approach a female of his own species—he considers his mission accomplished. This means that one of the females' eggs may remain unfertilized, and the population of this species will decline. This, of course, is only to the advantage of crucian carp—the fewer fish of other species in the lake, the less competition there is!