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J. Perelman
"Entertaining physics". Book 2.
Chapter 9. Reflection and refraction of light. Vision


But there is another way to solve the problem of "cap of darkness". He is in the color of the items in the appropriate colour, making them invisible to the eye. He often uses nature: giving their creation of a "purist" coloring, in the broadest scale use this simple tool to protect their creations from enemies or to ease their difficult struggle for existence.

What the military calls "protective color, zoologists since Darwin called protective or cryptic colouring. Examples of such protection in the world of animals can lead to thousands; we meet them at every step. Animals that live in the desert, have for the most part the characteristic yellowish color of the desert; you will find this color and the lion, and among birds, and a lizard, spider, worm, word, all representatives of the desert fauna. In contrast, animals that inhabit the snowy plains of the North - whether it is dangerous polar bear or a harmless Loon - endowed by nature white color, making them invisible on the background of snow. Butterflies and caterpillars living on the bark of trees, have the appropriate color, with amazing accuracy reproducing the color of tree bark ("the nun" and others).

Every collector of insects knows how difficult it is to find them because of the "khaki", which was given to their nature. Try to catch the green grasshopper, whirring in a meadow at your feet, you will not be able to see it on a green background, absorbing it completely.

The same applies to water inhabitants. Marine animals found among the brown algae, all have a "protective" brown color, making them elusive to the eye. In the area of red algae dominant "protective color is red. Silvery fish scales - too "protective". It protects the fish from birds of prey looking for them from above, and from predators, water, threatening them below: the water surface is mirrored not only the view when viewed from above, but even more so when viewed from the bottom of the water column ("total reflection"), and it is this shiny metal background merges silver fish scales. And jellyfish and other transparent inhabitants of water - worms, crustaceans, mollusks, sebaceous - elected as its "protective color full transparency and transparency, making them invisible in the surrounding colorless and transparent elements.

"Tricks" of nature in this respect far superior to human ingenuity. Many animals have the ability to change the hue of his "protective" color according to the change of environment. Silvery-white ermine, obscured by snow, would lose all the benefits of protective coloration, if the melting snow has not changed the color of his skin; and, behold, every spring white animal gets a new coat of red color, blending with the color Nude from snow, soil, and with the onset of winter again greyish, being enveloped in a white winter plumage.

Entertaining physics J. Perelman


System Orphus


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