Bird feather. Zipper closure on bird feathers Black plumage of birds

How does a pen work?

Protein-based feathers are made from a substance called keratin. Keratin is a strong and durable material formed as a result of the death of old cells that are located in the lower layer of skin tissue and die, moving away from sources of nutrition and oxygen and making room for young cells.

Bird feathers are designed to be so complex that it cannot be explained by the evolutionary process. Renowned ornithologist Alan Feducchia notes: "The whole distinctive feature of a feather is that it has aerodynamic properties. Feathers are light, have lifting power and easily return to their previous shape." And Feducchia reacts to the failures of the theory of evolution as follows: “I cannot understand how such an organ, which was originally conceived and planned for flight, could have originally appeared for other purposes.”

This pen device also made Darwin think. In his own words, the extraordinary beauty of the peacock's feathers gave him a headache. In a letter to his friend Asa Gray dated April 3, 1869, Darwin writes the following:

"I have lost interest in my own theory because I always think about the eyes on peacock feathers. Over time, I came to terms with this problem. Currently, I am very worried about some devices in nature, the existence of which we had not noticed before. I, for example, come to confusion when I see a peacock feather.

FEATHERS AND HOOKS
If you examine a bird's feather under a microscope, it becomes clear how unusually it was conceived and executed. In the middle there is the well-known long and hard tube. And on both sides of this tube there are hundreds of small feathers. It is the varying degrees of softness and varied sizes of these feathers that underlie the aerodynamic properties of the bird. However, what is most interesting is that on each of the feathers there are even smaller and invisible fibers called fluff. There are small hooks on this cannon. Thanks to these hooks, each fluff is, as it were, connected to each other with a zipper. To better explore this magnificent creation, consider a crane feather. One feather has 650 thin feathers on both sides of the tube, and on each of these feathers 600 feathers are randomly arranged. All these fluffs are connected to each other using 390 hooks. And the hooks are fastened on both sides, like in a zipper. The fluffs are pressed so tightly against each other by these hooks that they don’t even allow air to pass through. If the hooks somehow become separated from each other, then the bird only needs to shake itself or, in the worst case, clean the feathers with its beak to return them to their previous state.

In addition, birds, by fluffing their feathers, do not allow their body temperature to decrease. In hot weather, the feathers, pressed tightly to the body, do not allow the heat to pass through.

The theory of evolution teaches that birds evolved from reptiles. However, it is unable to explain the enormous difference between these two classes of living beings. Birds exhibit properties that differ from reptiles: they have a skeletal structure consisting of hollow and extremely light bones, have a unique respiratory system, and are warm-blooded creatures. Another unique difference that creates an unbridgeable gap between birds and reptiles is feathers.

The phrase “light as a feather” describes the perfection of the complex structure of a feather. The design of bird feathers is so complex that evolution simply cannot explain it. Scientist Alan Feduccia says feathers have "a structural complexity that provides mechanical and aerodynamic perfection that has never been achieved by other means."

The design of the feathers gave Darwin pause. Moreover, the ideal aesthetic feathers of a peacock had, in his own words, a depressing effect on him. In a letter to Asa Gray dated April 3, 1860, he wrote: “I well remember the time when the thought of an eye made me tremble, but I have overcome that phase...” Then he continued: “... and now the minute details of this structure make me feel uncomfortable . Seeing the tail feathers of a peacock every time I look at it depresses me!”

Examining the bird's feather under a microscope reveals a stunning design. As you know, there is a rod in the middle of the feather. Hundreds of small barbs emerge from each side of the shaft. The beards of varying softness and size give the bird its aerodynamic nature. Moreover, each barbule has thousands of barbules attached to it, which cannot be seen with the naked eye. These barbs are held together by means of hooks.

The hooks snap together like a zipper. These barbules close together so tightly that even smoke directed at the feather cannot pass through it. If the hooks come off for any reason, the bird can easily restore the feathers to their original shape by shaking itself or straightening the feathers with its beak.

To survive, birds must keep their feathers clean, well groomed, and always ready to fly. They use an oil-secreting gland at the base of their tails to keep their feathers in shape. They use this oil to clean their feathers. This oil also provides waterproof protection when birds swim, dive or fly in the rain.

In addition, in cold weather the feathers keep the bird warm, preventing its temperature from dropping. In hot weather, the feathers are pressed closer to the body.

Even a superficial acquaintance with such a unique system as a bird’s feather allows us to conclude the existence of a Creator, Whose limitless intelligence ideally designed and brought into existence the world around us.

American scientists, intrigued by the deep black color of the feathers of some species of birds of paradise, studied their structure under an electron microscope. It turned out that the black color is not due to pigments - melanins - as is usually the case in birds. It's all about the structure of the feather barbs, at the ends of which there is a “fringe” of nanogrowths. This structure perfectly absorbs light - up to 99.95% of the visible spectrum, which leads to a very rich black color. In terms of absorption, bird of paradise feathers are close to Vantablack, the blackest known material.

In living nature, color can be formed in two ways - pigmentary and structural. In the first case, it occurs due to special molecules - pigments, which selectively absorb, reflect or emit light with a certain wavelength. In the second case, the color depends on the structure of the surface on which the light falls and which selectively absorbs and/or reflects it. Structural coloring is described in detail in the article by T. Romanovskaya. A particular variant of structural coloring is structural absorption, that is, the absorption of light by a surface. If all or almost all of the visible spectrum is absorbed in this way, a black color is obtained.

Black plumage of birds

In most birds, the black color of plumage is due to pigments - melanins. They are responsible for the blackness of birds well known to us - crows, rooks, blackbirds, etc. In addition, in some birds, due to the correctly ordered fibers of the upper layer of keratin, iridescence occurs (a variant of structural coloring). Iridescence is expressed in iridescent tints and/or metallic luster.

“Elements” is already about the unusual behavior of males of the wonderful bird of paradise. When courting a female, the male folds his wings and spreads his feathers so that he ceases to look like a bird at all (Fig. 1, g)! Experienced observers have noticed another feature of this and a number of other species of birds of paradise (family Paradisaeidae). The black color of their plumage visually appears darker (blacker) than the black plumage of other birds (Fig. 1). Recently, a group of scientists from the USA confirmed this observation and, most importantly, figured out how this effect occurs. To do this, the researchers studied the black feathers of seven species (all depicted in Fig. 1) - six species of birds of paradise and one species - Melampittidae - from a closely related family (Melampittidae). Melampitta and paradise crow have black coloration due to melanins, that is, their black color is quite normal. And the rest of the birds of paradise in the study have “super black” plumage batches. They are typically used in mating displays. Some species, such as the wonderful bird of paradise, have regular melanin black feathers in addition to super black feathers. They are located on the back and during mating the male does not specifically show them to the female. Scientists studied not only the super-black feathers of this species, but also ordinary ones taken from the back.

To begin with, the feathers were studied using a spectrophotometer and a deuterium-halogen light source DH-2000-BAL from Ocean Optics. This source, thanks to deuterium and halogen lamps, as well as special filters, can, in particular, produce output light of a given intensity, which equally represents the entire visible spectrum. This avoids distortions in the spectra of the samples being studied, since they are illuminated by a balanced light beam.

Spectrophotometry has shown that the super-black plumage reflects only 0.05–0.31% of light (that is, absorbs up to 99.95% of the visible spectrum). And ordinary black feathers (paradise crow, melampitta, and those taken from the back of the wonderful bird of paradise) reflect one or even two orders of magnitude more: 3.2–4.7% of radiation (Fig. 2).

These values ​​indicate that the light absorption capacity of super black bird of paradise feathers approaches that of man-made materials with a very high absorption rate. Thus, the blackest material available today absorbs 99.965% of visible light. Vantablack consists of vertically oriented carbon nanotubes, and absorption occurs due to the fact that light penetrates into the material, where multiple reflections occur from the walls of the nanotubes.

In addition to the feathers of birds of paradise, the wings of some butterflies absorb light well. Absorbing up to 98-99% of visible light, they also appear very black. This is due to the special microstructure of the scales. (Recall that the wings of butterflies are covered with small scales that overlap one another like tiles.) Super black scales of a male butterfly Troides aeacus from the sailboat family (Papilionidae, Fig. a) they consist of an upper anti-reflective part and a thin film underneath it. The upper part consists of evenly distributed Λ-shaped ridges. The ridges are connected to each other by bridges - veins. As a result, a lattice with elongated holes with dimensions of about 490 × 380 nm (and a diagonal of about 620 nm, Fig. c-e) is formed.

Since the wavelength of visible light falls in the range of 380-780 nm, the holes are sized to allow most of the visible light to pass through. Photons of light “enter” the holes and are reflected from them many times. Light with a longer wavelength is reflected mainly from the ridges, since it cannot pass inside the holes. Repeated reflection leads to absorption of light - just like in the case of Vantablack.

To understand the unusual features of the black plumage of birds of paradise, scientists used a scanning electron microscope. As is known, bird feathers consist of a shaft from which first-order barbules extend, from which, in turn, second-order barbules extend (see Shaft, barbs and hooks). The beards of the first and second orders are located more or less in the same plane, forming the fan of the feather.

It turned out that the super-black feathers of birds of paradise have a special structure of second-order barbs. First of all, the tips of the second-order barbules diverge into many microprotrusions that form a fringe (Fig. 3). There is one more feature: the barbs of the second order are, as it were, raised above the plane in which the shaft of the feather and the barbs of the first order are located. As a result, they form a dense (due to microgrowths) layer, rotated approximately 30° towards the tip of the pen.

The layer of tiny nanogrowths is responsible for absorbing light. The fact is that the cross section of microgrowths is less than the wavelength of light. This allows light to penetrate into the pen. Thus, some of the light hitting the pen is absorbed and some penetrates, but almost nothing is reflected out. Inside the feather, photons of light are again reflected, and some of them are again absorbed. Due to the large number of microgrowths, multiple reflections occur, and each time some part of the light is absorbed. This results in the feather absorbing most of the light. In general, the absorption principle is the same as that of Vantablack.

Due to this structure of the feather, in general, it does not matter what pigment color it has. After all, virtually all the light is absorbed anyway. Researchers confirmed this in an original way: they covered the feathers with gold dust. The ordinary black melapitta feather (the black color of which is due to melanins) became golden after this operation. But nothing happened to the super-black feather: it remained black, absorbing most of the visible light (Fig. 4).

It is interesting that in birds of paradise, like butterflies, super-black areas are often adjacent to spots of very bright colors, as if shading them. Based on this observation, scientists hypothesized that the super black color evolved to highlight the bright colors of the plumage. And those, in turn, can play a role in mating behavior. For now, however, this is just a hypothesis.

Since childhood, people's attention has been attracted by winged creatures soaring in the sky - seagulls, pigeons, tits, magpies. Tiny sparrows are jumping funny around the puddles. Everyone is familiar with this picture. And so, at an older age, someone, not forgetting the joy of childhood, chooses the profession of an ornithologist or zoologist. In the article we will tell you and show photos of what a bird’s feather looks like under microscope- this exciting spectacle is no less interesting than increasing the fur of animals. And most importantly, obtaining biological material for research will not be difficult. But first, a little theory so that your observations are supported by knowledge and facts.

bird feather- this is a formation consisting of a cutaneous horny substance and has the most important functional significance for mechanical movement and protection from external natural factors. Between the bare areas of thin boneless skin, pterilia are systematically located - feathers grow from these small depressions.

The plumage allows you to fly, increases the load-bearing capacity of the wing and its span, and makes the body shape streamlined. Without it, large birds would not be able to fly into the air. Another important function is thermoregulation. When unfavorable weather occurs, frosts, winter colds, heat is retained inside the body as much as possible. And in the summer heat, on the contrary, it gives off abundantly. By the way, some species of ancient dinosaurs were also feathered, but unlike birds (considered their only surviving descendants), the cover resembled a fine, hairy fluff.

In the course of evolution, it gradually turned into real feathers, which (this has been proven) were already present, for example, in the bright representative of the Lower Cretaceous era, Sinornithosaurus.

Structure bird feather:

• Trunk or central rod. This is a kind of axis of symmetry, a feather base. It ends with a feather bursa deepened into the epithelium;
• Fan (outer and inner plates). They represent a network of connected numerous barbs ending in hooks (serve for adhesion to neighboring ones);
• The bare part of the feather shaft is called the feather stem. This is a translucent horny tube, hollow from the inside.

To see a bird's feather under a microscope Care must be taken to select the correct equipment. It is advisable that your model have two illuminators - the lower illumination will allow you to see the smallest details of the feather structure “in the light”. And the top one will provide, at low magnification, a wide coverage of a large area of ​​the sample in its natural color range. The presence of a video eyepiece will make photography possible. To install it, a regular eyepiece must be pulled out of the eyepiece tube, and a camera must be inserted in its place (their mounting diameter is the same and is 23.2 mm). The visualized image enters the sensor matrix and is transmitted via USB to the computer. And already in the program window, by pressing interactive buttons, photographs and videos are taken.

The finished micropreparation is included in the set “Micromed - Botany and Zoology -14”.

To prepare a similar microsample yourself at home, you need to use a slide and cover glass - place a piece of biomaterial between them, smooth it with a preparation needle or tweezers, drop a drop of colorless fir resin and press the glass surfaces tightly.

Primary focusing is carried out at low magnification, then, when the image becomes clear, you can change lenses to more powerful ones.

The scientific approach becomes inextricably linked with modern research technology and magnifying optical instruments. We recommend school light microscopes for viewing feathers: Eureka 40x-400x, Levenhuk Rainbow 50L, Bresser Junior 40x-1024x.

Overalls and jackets, boots and boots, bags and wallets, tents and backpacks, all this is miraculously easy and simple to fasten if there is a zipper.

(the image of the principle of operation of a zipper is copied from the famous Wikipedia)

Did you know that the first zipper was invented more than a hundred years ago and had a slightly different principle of operation than today?

The first zipper consisted of two chains, with hooks and holes, clinging to each other using a movable key - a tongue.

“Shoe fastener” is what the American Whitecomb Judson called his invention. The invention was intended for a sick friend who injured his back while saving a girl during a fire. It was very difficult for him to lace his shoes and he asked an inventor friend to come up with something that would make putting on shoes easier.

So says the legend, but we don’t really know what it was like, just as we don’t know what told the inventor the principle of operation of the fastener? Maybe structure of a bird's feather?

After all, a bird's feather has connections very similar to those of a zipper. But, unfortunately, they can only be seen under a microscope.

The barbs extend from the feather shaft in both directions, forming the feather fan. Branches also extend from the barbules in both directions - barbules. The structure of these barbules contains the main secret of the strength of bird plumage: some of the barbules have hooks that cling to other barbules without hooks, but with a groove on the edge.

Thus, the individual beards firmly adhere to each other, forming a thick and durable mesh plate. It turns out that the individual elements of a bird's feather are firmly connected to each other, almost the same as parts of a zipper.

In each feather, if you look at it under a microscope, you can count hundreds of thousands of barbules and millions of their branches with hooks.

And although you may not have a microscope, take your child to examine a bird's feather.

To do this, you will need a contour bird feather (as in the photo); it can easily be found in the park or in the poultry yard.

Run your fingers along the fan. Do you feel that the beards are holding each other tightly enough?

Now try to tear off individual beards. Happened? In this case, it was necessary to expend some effort to get the hooks to pop out of the grooves.

Now try to restore the connection, to do this, place your index finger on the bottom and your thumb on top of the feather, and, squeezing your fingers, run them along the gap in the barbs, as if you were fastening a zipper. If the pen is not too frayed, the connection will be restored. And if it doesn’t work, it means the hooks have already broken, because they are so fragile.

Birds reconnect their barbules by “fastening” them with their beaks. In order for the “clasp” to work properly, the bird carefully cares for its feathers. I’ll tell you how they do this another time.

And finally, I want to note that the beards of feathers are not always interlocked with each other. For example, the beards of down feathers do not have hooks or the beards at the very bottom of the feather - this is the downy part of the fan, the function of which is to hold a layer of air against the skin.

The barbs of the feathers of some birds, for example, ostriches, do not have hooks. Such feathers are called loose feathers and are particularly soft and beautiful.