Sea "lazebos". part 3
Life at the bottom has many attractive sides for the flounder, but - "there is no rose without thorns" - and it has its own thorns. A lying way of life leads to a loss of the ability to move quickly. Kambhals float flat, clumsy, wriggling their flat bodies, swimming slowly, barely changing direction. Fewer flounder with a narrower body can swim like other fish, holding upright. It is clear that under these conditions, it is difficult for a flounder to escape the persecution of predatory enemies if they notice it. In those cases where the speed of the legs can't help, it's often the "invisible hat", in the form of protective coloring, that's why this technique is so widely used in modern military science, where no speed of movement can save from the current envelope bullet!...
And so, on the flounder, we can observe a number of amazing devices in the sense of different development of protective coloring. First of all, the usual coloring of the upper side of the body is always more or less the same color of the environment, ie, the bottom that the fish lies. Most flatfish have brownish, blackish, sometimes dotted with light dots, spots or marble divorces, according to the color of the pebble bottom:
What's more, many flounder have an amazing ability to change their color and adapt it to the bottom color. Chameleons and cephalopods are known to have a similar ability.
This flounder is usually brownish but is dotted with small and large yellowish and white spots.
Zoomer placed the flounder in an aquarium, the bottom of which was covered with either uniform light sand, or dark soil, or light gravel on a dark background. In all these cases, it was found that after a short time the fish took on a similar color to the surrounding bottom, and received a motley pattern of light spots.
On a light background of yellowish sand after a day, the fish loses its dark coloring, becomes evenly yellowish, hardly noticeable, merging with the general background. The same result is obtained by placing it in an aquarium with a white marble bottom.
If the soil consists of coarse, colored sand, the fish adapt to it, getting a fine spotted pattern on a dark background, and in this case, it is probably the least noticeable.
Even more remarkable, however, are the results of Zoomner's experiments with artificial soil, in the form of a chessboard or blackboard with rounded white spots. It turns out that in this case, which is hardly possible in nature, the fish adapt to the ground. In the first case, angular (though not square) light spots appear on a dark background, and in the second case, the spots are rounded. As long as the fish is on the appropriate ground, so long as its color does not change significantly. However, it is worth transplanting the same flounder into an aquarium with another soil, and, little by little, the color will change accordingly.
Absolutely the same as in chameleons, and in this case, the change in color caused by movements - contractions and pulling, lifting and lowering in the skin cells, loaded with grains of dye, pigment, called "chromatophores". By exposing more or less pigment grains on the surface, these cells make this skin area darker or lighter.
But the question is, how do you reproduce the skin's environmental coloring? Is it possible that the environment acts beyond the visual organs?
These questions were answered in the 1970s by the French zoologist Pouchet, and his experiments were exactly the same as those of Sumner. They both dazzled flatfish, and it was surprising to find that fish without eyes were losing their ability to adapt to their surroundings.
From this it is clear that the coloring of the environment, automatically (or, as physiologists say, reflexively) is transmitted through the organs of vision, eye nerves, brain, and spinal cord, and through the nerves that supply their branches of the skin, those pigment cells, chromatophores, the contraction of which occurs from one or another color.
If you blind the flounder, who lived on a light ground, evenly yellow, it will remain so. If you do the same operation of dazzle over the flounder, previously sitting in an aquarium with gravel and managed to take the appropriate color, it retains its pattern, even if transplanted into the light soil ...
The mystery of changing the color of flounder can be considered these experiments, at least to some extent solved, and you can only marvel at the accuracy with which this reflex mechanism works. It seems to photograph the environment on the skin of fish!
We can see from all the above said that the "sea lazybones", thanks to the remarkable features of their existence, have acquired many unique features of the organization. This confirms to us for the 1001st time how closely the structure of living beings is connected with their way of life! We see a remarkable harmony here - harmony established thanks to many hundreds of thousands and millions of years of continuous struggle for existence and continuous improvement!