This amazing fish: It took only 90 days to complete hundreds of millions of years of visual "evolution"

A group of newly hatched black sea bream fry are experiencing the most thrilling transformation in their lives: their body length is only 3 mm, and their retinas are like an undeveloped film, which can only perceive blurry light and shadow. However, in the next 90 days, these fry will add an average of 23,000 cone cells per day, reenacting the 380 million years of visual evolution of their ancestors. This folding of individual development and systematic development in time and space reveals the deepest survival wisdom of life.

Day 1-7: Starting from a monochrome world

The newly hatched black sea porgy fry is only 3 mm long, and its visual system is like that of primitive fish in the Cambrian period - a "black and white vision" dominated by monochrome rods. At this time, the retina is like an old film camera: it can only see ultraviolet light, and can only receive 365nm ultraviolet light to identify the weak fluorescence of plankton; the reaction is extremely slow, and it takes 0.12 seconds to react when seeing prey (humans only need 0.1 seconds to blink); the survival strategy is to rely on the feeling of the skin to stay alive, and there are "water flow sensors" on the body that can detect water flow like the movement of hair; at this stage, the predation success rate of young fish is only 2%, and they can only succeed once in 10 predations, which is as clumsy as the ancient fish 500 million years ago.

Day 7-30: The outbreak of the two-color revolution

On the seventh day after hatching, the fish's eyes suddenly began to upgrade like crazy, and a "Cambrian explosion" at the genetic level took place in the young fish's retina. The thyroid hormone receptors were activated, triggering the crazy proliferation of cones: during this stage, the retina will undergo reconstruction, and the density of their foveal cones will soar, with 23,000 new photoreceptors added every day - equivalent to adding a large number of pixels to the camera every day; they can see blue and green at the same time, and can identify the outline of prey against the background of algae; the predation response becomes 5 times faster: the predation time is shortened from 5 seconds to 0.8 seconds, and the accuracy of phototropism behavior reaches 78%; scientists have found that the genetic changes at this time are exactly the same as when fish first evolved color vision 300 million years ago, perfectly reproducing the visual upgrade of bony fish in the Devonian period.

Day 30-60: The foundation of trichromatic vision

The full-moon black sea bream unlocks new skills. The 30-day-old fry enters the "Cretaceous mode" and the retina begins to evolve in layers:

The newly added cone cells can recognize the outline of prey under the background of green light, and can clearly see the small insects in the water grass pile; neural upgrade: the complexity of bipolar cell dendrites has increased by 3 times, and it has the initial ability to compare and analyze colors; extend the foraging time: with the help of weak red light, it can find food for 1.5 hours more in the evening; the success rate of predation in this stage has increased by 5 times, and it can catch prey 6 times out of 10 attacks. This is equivalent to repeating the visual evolution of fish in the dinosaur era 100 million years ago.

Day 60-90: The coronation of the four-color king

In the last 30 days, the young fish experience the ultimate evolution of their visual system: they can see ultraviolet light that humans cannot see, and can distinguish between red, blue and green; they have superb dynamic vision, and can lock onto prey at a speed of 30 kilometers per hour (faster than an electric bicycle); they can predict the position of prey 0.5 seconds in advance, with an error of less than the thickness of a coin. At this time, their eye structure is exactly the same as that of their ancestral fossils 23 million years ago. But the cruel thing is that during this period, 94% of the "unsatisfactory vision" fish were eliminated by nature.

This visual transformation is not a one-man show of genes, but also requires precise chisels - environmental factors, among which salinity and light regulate their development: first, the saltiness must be just right, too light or too salty water will slow down the development of the eyes; second, blue light is needed, and specific blue light exposure every day can speed up the reaction speed by 22%; then, complete darkness can cause blindness, and without light, the eye nerves will atrophy by 63%. Just like human babies need nutrition and stimulation to develop, the eyes of small fish also need a specific environment to grow perfectly.

When the sun shines through the nursery pond on the 90th day, the surviving black sea bream fry have completed the ultimate evolution of their visual system. On their retinas, four types of cones are precisely arranged, and the neural circuits operate at quantum efficiency - this system is not only a weapon for individual survival, but also a genetic memory of the species that has lasted for 380 million years. In the 90-day space-time folding of life, each fry is reenacting the evolutionary epic of its ancestors. Their eyes tell us: the greatness of life lies not only in the long evolution, but also in the transformation that condenses billions of years of wisdom into an instant.

References:

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