The four-eyed fish is a member of the Amazon River that spans the Amazon rainforest. Its magic lies in its "four eyes". What's even more surprising is that from birth, there is bound to be a "husband" or "wife" to match it, because only when you match can you mate!
You can't catch the magical "four-eyed fish"!
The "four-eyed fish" is only about 30 cm long and is a small fish. It mainly lives in the marginal zone of seawater and fresh water in the mouth of Amazon River, and it is an omnivorous fish. "Four-eyed fish" actually has only two eyes, but its eye structure is very strange. From the middle of the eyes, from front to back, there is a black horizontal eyelid membrane that divides the eyes into upper and lower parts. The upper part is raised to observe the movement above the water surface, and the lower part observes the part below the water surface. These upper and lower parts cover all the visual angles of water and underwater, which is almost 360 spherical vision with no dead angle!
The upper part of the "four-eyed fish" has very keen eye vision. When it finds insects flying at low altitude, it can judge the flight path of insects and jump up and swallow them directly! Coupled with its 360-degree spherical vision, threats are discovered by them when they approach from far away, so if you want to catch them, you really have to find ways, such as using traps and casting nets, which may not work for them!
The magical eye structure of four-eyed fish
Scientists are also curious about how this fish looks at things. On April 5, 20 17, the Royal Society published a paper on the causes and genes of the eye structure of the four-eyed fish, and introduced the eye structure and development process of the four-eyed fish in detail:
In fact, the "four-eyed fish" actually had two eyes when it first hatched. As it grows up, the pupil always wants to contract, and the cornea and pupil are divided into two halves and continue to develop completely. Finally, when they grow up, the corneas and pupils of the upper and lower "two eyes" are complete, as shown in the following figure:
Although the upper and lower eyes belong to the same eye, its internal structure is two sets of retinas. The upper retina is underwater, and the off-duty part is above the water. Are you a little dizzy? Look at the eyeball structure chart to understand!
Eyeball structure of four-eyed fish
This kind of eye is almost perfect for aquatic fish, which can not only deal with threats from the air, but also take into account the underwater environment at the same time. But the question is, how does this little brain of the four-eyed fish handle this vision from four retinas? Scientists are also very curious, but unfortunately it is not involved in the paper!
Head structure of four-eyed fish
The male-female pairing of four-eyed fish is even more amazing.
In addition to the stunt of seeing four roads, the four-eyed fish can persist on land for a while, because it has a liquid sac on its head, which can keep its gills moist after coming out of the water and exchange oxygen directly in the air, so it can live in a short time.
But even more surprising is the pairing of four-eyed fish. There are two kinds of scales covering around the cloaca of female fish, one is that the scales cover the left side and the other is that the scales cover the right side. Of course, it doesn't matter if it is reversed, because the male fish has a particularly deformed anal fin that matches this direction, one to the left and the other to the right!
When the female fish along the scale meets the male fish on the right, it is a good thing, otherwise, the two will never match! The female fish with lamella can also be paired when they meet the male fish on the left, but they have to change positions. So it should be super-spatial, can you understand it, haha!
Therefore, the four-eyed fish don't have to worry about finding a wife, because half of them are always reserved for them!
Further reading: Terrible fish drilling in the Amazon River!
If you know that there is a fish in the Amazon River, it will crawl into the urethra along your tintin and swim to the bladder! Dare you swim in the river? This is the famous toothfish in the Amazon River. It is particularly sensitive to the current, so when you release it in the river, it can feel the current and go upstream to the source!
In other words, your bladder is wide and full of urine. Although this living creature won't bite you, it can still make you roll on the ground in pain, so this kind of pain is actually understood by women, thinking that it is more convenient for toothfish to enter when women pee in the water than men. So when swimming in the Amazon River, please put on tight boxers and don't pee!
Of course, if you are not afraid of piranhas!