feather

Bird feathers

Clearly visible, spread out flight feathers and control feathers of flying Dominican gulls

Springs ( latin pennae , singular Penna ) are from the outer skin of the birds (and fossil feathered dinosaur formed), in the finished state inanimate structures from keratin , together as feathers or plumage form the main outer surface. The branch of science that deals with feathers is called plumology .

Feathers protect the birds on the one hand from water and cold and on the other hand they provide them with colors that serve both as camouflage against enemies and as a means of visual communication . In addition, there is the firm contour that they give the bird and the support of flight ability . Although a single feather is extremely light in weight, a bird's plumage weighs about twice as much as its skeleton .

etymology

The altgerm. Noun mhd. Veder [e] , ahd. Fedara is based on the idg. Root pet- "to fall down on something, shoot, fly".

Types of feathers

Wing feathers of the common buzzard

Down

There are two basic types of springs that differ in construction. These are firstly the contour feathers , comprising the exterior of the body, on the other hand located under the coverts lower springs (also down or dunes), which act as a heat-insulating layer. The cover feathers protect the down feathers from moisture.

Contour springs

The contour feathers ( Pennae conturae ) are functionally further divided into:

Body feathers ( Pennae conturae generales ): the cover feathers of the trunk

Flight feathers ( Remiges ): They form the actual wing of the wing on the hand ( hand swing ) and forearm ( arm swing )

Feathers ( rectrices ): the tail feathers

Cover feathers ( tectrices ): the remaining feathers on the wings and tail

Lower springs

The down or down ( plumae ) form the undergarment. Some birds (e.g. ratites ) do not have them.

The nestling down , the plumage of the young birds, is not real down, but modified contour feathers. They also protect against the cold.

Special springs

In addition to these two basic types, there are also various special springs:

Semi- dunes ( Semiplumae ): They are under construction between contour feathers and dunes and are located at the transition to the areas without body feathers.

Thread feathers ( Filoplumae ): Your follicles are well innervated, they serve the proprioception of the feather position. Thread feathers missing the ostriches and cassowaries .

Bristle feathers ( Setae ): They replace the eyelashes, in some bird species they are also developed as nasal bristles on the nostrils.

Powder feathers ( Pulviplumae ): They are found in some birds (e.g. pigeons, waterfowl) and produce a fine, water-repellent dust from keratin granulate.

construction

Schematic construction of the contour spring: 1 shaft, 2 coil, 3 flag ( 3b outer, 3a inner flag), 4 secondary spring, 5 upper umbilicus, 6 lower umbilicus, 7 spring branch, 8 arc ray , 9 hook ray

Contour springs

The contour feathers consist of a long and firm quill pen ( Scapus ) and a feather plume ( Vexillum ), which is formed from the narrow outer plume ( Vexillum exterior ) and the wide inner plume ( Vexillum interior ). The keel is further subdivided into the feather shaft ( Rhachis ) and the feather coil ( Calamus ). There are two openings on the coil: an upper umbilicus ( superior umbilicus ) and a lower umbilicus ( inferior umbilicus ).

Feather branches ( barbae or rami ) extend from the spring shaft ( rachis ) to the front and back , from which again arc rays ( barbulae proximales ) and hook rays ( barbulae distales ) arise. There are fine hooks on the hook rays, which interlock with the arc rays of the neighboring spring branch and thus create the necessary rigidity and strength of the spring vane.

Remaining feathers

The down (or dunes ) have a short shank and hook sheet and beams (Dunenäste or Dunenstrahlen) which are not entangled with each other so as to form no spring flag. The special feathers only have a shaft and a tuft of short, non-toothed branches.

plumage

Plumage of a griffon vulture

The totality of the springs as feathers or feathers called.

Distribution of feathers on the body

The feathers are not evenly distributed on the body. They overlap in such a closed manner that this is not visible from the outside. A distinction is made between:

Federraine ( Apteriae ): districts without body feathers

Feather corridors ( pterylae ): districts with body feathers

An exception are e.g. B. penguins , in which the body is evenly covered with feathers.

Dune dress, juvenile dress and adult dress

The young of some families of the birds hatch naked, e.g. B. in bee-eaters , kingfishers , cuckoo birds , rackets , woodpeckers and sailors . The young of the other families are covered with dunes when they hatch . These nestling downs are not real down, but modified contour feathers. The Dunenkleid is at nest stools mostly monochrome and less dense than precocial birds , which are significantly stronger Camouflage and isolation function.

The contour feathers growing from the same papillae push the downs out. The juvenile or youth dress follows the dune dress. This is replaced with the first moult by the adult dress or other youth clothing such. B. with sea eagles or larger seagulls . Downy and juvenile plumage often differ significantly in color from the plumage of adult birds.

Magnificent dress and plain dress

With the start of the breeding season, males of some bird species with a seasonal dimorphism change into a strikingly colored splendor (also breeding or summer dress). It is used to advertise partners and to delimit the territory. After the end of the mating season, they then change to a more inconspicuous, plain dress (also resting or winter dress), which offers better camouflage and thus better protection against predators .

coloring

Plumage of the blue peacock

James Flamingos , Bolivia

The color of the feathers is mainly caused by the brown to black pigment melanin . Other pigments are carotenoids and porphyrins . The interaction of the light absorption of these pigments with the light-reflecting air deposits in the feathers creates a wide variety of colors. The often shimmering effect is based on interferences in the regular fine structures of the feather (see structure colors ).

The color can also be changed by wearing the colored nibs and applying a dye. In this way, the body's own, brownish secretion from the root gland can be applied. The orange color of the adult dress of the bearded vulture is caused by bathing in iron-containing mud.

In addition, the plumage of many birds has a pattern in the ultraviolet range that is invisible to the human eye . In many cases, it can be assumed that the ultraviolet reflections have a specific signaling effect, for example when choosing a partner. Many birds can see ultraviolet light, but not all, such as no nocturnal birds. There is a correlation between the ability of a species to perceive ultraviolet light and the presence of a reflection maximum of the plumage in the ultraviolet spectrum.

A special phenomenon is the pink to red coloration of the naturally white feathered flamingos . The pink color of the plumage is due to the ingestion of carotenoids with food. These are mainly found in planktonic algae . The flamingo organism can convert these carotenoids with the help of enzymes in the liver ; this creates several pigments , especially canthaxanthin , which is stored in the skin and feathers of adult flamingos. Young birds have gray plumage with little or no pink pigments. The often unnatural diet of zoo flamingos means that they have more white plumage there.

Development of the bird feather

Feather structure of a yellow and breasted macaw

Spring systems are developed from around the 5th day of life (in the egg). Cones grow out of the epidermis and later sink into the skin to form follicles or bellows . When these are ready, they consist of a central cone, the papilla, which is enveloped by epidermis. The cell divisions from which the spring emerges take place at the base of the follicle, the formation zone (epidermal collar). This means that the most differentiated parts of the growing feather are at the distal end (top). The uppermost cell layer of the epidermis divides outwards and becomes keratinized, ie the cells keratinize and die. This creates a protective covering around the papilla, the spring sheath . This is initially closed distally, the spring branches are still in it at this point in time. The spring is formed in the typical form with a shaft and the side branches, although the side branches are first formed in a spiral at the edge of the formation zone and these then merge centrally to form the shaft. The feather sheath also protects the lower part of the rachis with side branches and the well-perfused formation zone. The feather sheath is also known as a blood quill , as blood leaks out in the event of injuries as long as the feather has not finished growing.

The genetic control of the development of the feathers is carried out by two genes , which generally act as signal transmitters for the growth of limbs, fingers and skin structures in vertebrates. These are the genes Shh (Sonic hedgehog) and Bmp2 (bone morphogenetic protein 2) as well as the associated proteins . Shh stimulates the cell division of the keratinocytes , while Bmp2 controls the differentiation of the cells and takes over the regulation of growth. The distribution of the concentration of the two proteins also defines the top and bottom of the feather.

Feathers are regularly renewed during the moulting period . During the moult, new feathers grow from the same follicles from which the old ones fell out. The same education zone is active again.

Diseases and developmental disorders

Evolution of the bird feather

Archeopteryx fossil feather

Stages in the evolution of the spring: 1 single filament, 2 several filaments connected to the base, 3 several filaments connected to a central shaft at their base, 4 several filaments along the length of the shaft, 5 several filaments emerging from the edge of a membrane structure, 6 Asymmetrical cover spring from the wing with shaft, barbs and spikes, 7 Asymmetrical cover spring with an asymmetrical (curved) shaft, 8 Undifferentiated flag with shaft

The widespread view that feathers are a further development of reptile horn scales has been revised by the findings of recent years. Today we know that the feather, like the hair coat of mammals , is an independent development that is not homologous with the scales of reptiles .

The evolution of the bird's feather probably took place in several steps. Fossil feathers do not provide any information about this, however, as the few fossil evidence of feathers already show very well developed bird feathers. For example, the ancient bird Archeopteryx from the late Upper Jurassic ( Tithonium , approx. 150.8 to 145.5 mya ) already had cover feathers that correspond to those of today's birds. In particular, the feathers that do not lie on the body axis are asymmetrically shaped, which benefits aerodynamics (and therefore, conversely, indicates the animal's ability to fly).

Nevertheless, it can be assumed that such a complex structure could not have been created in one step. The fossil record of feathered dinosaurs , such as B. Caudipteryx or Sinornithosaurus show differently developed precursors (proto-feathers) and thus confirm this theory. According to Richard O. Prum and Alan H. Brush, the bird's feather was created in the course of evolution over several steps:

The first springs were probably hollow rods, which also represent the first step in the development of today's springs. This preliminary stage of the feathers is already assumed in a number of dinosaurs belonging to the group of theropods (from which the birds developed), and could also be detected when the Sinosauropteryx was found. These hollow rods were created together with the epidermal collar.
The next stage is a tuft of feather, which is similar to today's down, but has not yet developed the secondary branches on the branches. Along with the evolution of this type is the differentiation of the epidermal collar.
In the third stage a separation of the two types of springs is assumed. The cover feather with the feather shaft is said to have been created here, but it does not yet have any hooked secondary rays, as well as the down feather with secondary rays, which can still be found today. A combination of the two could already have created the first cover feather with secondary rays.
In the penultimate stage, the cover feather with the interlocking flag was created. In contrast to today's feathers, this was constructed symmetrically and corresponds to today's contour feathers of the plumage. This feather could be found in the theropods Caudipteryx and Sinornithosaurus .
Most recently, the asymmetrical flight feather was created, which enabled active flight and corresponds to the forerunner of the flight feathers of today's birds. Already Archeopteryx had this spring.

In contrast to this theory, feathers were found in French amber in which secondary rays branch off from a central shaft to two sides, which are not connected to one another by hook and arc rays. The shaft of the spring consists of secondary rays that are still incompletely fused together.

Josef H. Reichholf takes the view that the feathers were originally a waste product of the metabolism - the body of the animals would have excreted superfluous or even poisonous sulfur-containing compounds in this way.

Feathers in Mythology and Customs

Feathers already had a sacred meaning in the religion of the Egyptians . After a person died, their soul was weighed against the pen of the mate . What soul was as light as the pen was not burdened by sins . In the Egyptian hieroglyphic script the pen therefore stood for the truth .

In the sacred ideas of many peoples, the feather was a symbol of the element air .

In the Roman religion , feathers and feather headdresses were used in the shrines of Juno .

In Celtic mythology , the feather of the wren was of particular importance: It was considered the sacred animal of the goddess Mana . Every year on the Isle of Man the wrens were killed with a great ceremony and their feathers were then distributed to the seamen as protection. A mythical creature with plumage in Ireland is the Augurey .

In the region of Bavaria, Tyrol and Salzburg there was the custom of the cutting pen. In the late 19th and early 20th centuries, lads went out in their free time with a straight white rooster feather on a straw hat. The term cutting refers to the scythe shape of the pen, but also stands for courage and boldness. When two fellows got into each other's hair, it was not uncommon for the cutting pen to be fought.

Feathers appear in a familiar phrase: " adorn yourself with foreign feathers ".

use

Feathers as ornament on a military headgear

Feathers have long been used to fill pillows , jackets, etc. In the past in particular, feathers were also used as decorative jewelry , for example for hats (see feather jewelry ). Quills used to be used as writing implements.

Feathers were and are used to fletch arrows .

Chicken feathers contain more than 80% protein - more precisely keratin . The hydrolysis produces L- cystine and a protein hydrolyzate from which amino acids are obtained commercially .

Application in bionics

Research carried out in April 2009 by the University of Genoa shows that springs are suitable for significantly reducing the air and water resistance of aircraft and underwater vehicles. Such vehicles could be operated much more efficiently covered with springs. The Italian scientist Alessandro Bottaro and his colleagues investigated the function of the inconspicuous cover feathers of birds' wings. They found that when the birds glided, some of the feathers protruded from the wing at certain angles, causing the airflow to vibrate. To investigate the effects, the researchers covered a cylindrical object (20 cm in diameter) with synthetic cover feathers and tested it in a wind tunnel . The result was a 15% reduction in air resistance.

literature

DS Peters: Problems of early bird evolution. I. The thing with the feathers. In: Nature and Museum. 11, 2001, pp. 387-401.
Richard O. Prum: Dinosaurs take to the Air. Nature 421, p. 323 (2003).
Richard O. Prum, Alan H. Brush: The Evolutionary Origin and Diservication of Feathers. In: Quarterly Review of Biology. 77 (3), 2002, p. 261ff.
Richard O. Prum, Alan H. Brush: First came the pen. In: Spectrum of Science. October 2003, pp. 32-41, ISSN 0170-2971 .
Einhard Bezzel: bird feathers. BLV, 2003, ISBN 3-405-16460-5 .
Einhard Bezzel, Roland Prinzinger : Ornithology. 2. completely reworked. u. exp. Edition. Ulmer, 1990, ISBN 3-8001-2597-8 .

Web links

Wiktionary: Feder - explanations of meanings, word origins, synonyms, translations

Commons : feather album with pictures, videos and audio files

Individual evidence

↑ Manfred Eichhorn (Ed.): Langenscheidt specialist dictionary biology English: English - German, German - English . 1st edition. Langenscheidt, Berlin et al. 2005, ISBN 3-86117-228-3 , p. 537 .

^ The dictionary of origin (= Der Duden in twelve volumes . Volume 7 ). Reprint of the 2nd edition. Dudenverlag, Mannheim 1997 ( p. 180 ). See also Friedrich Kluge : Etymological dictionary of the German language . 7th edition. Trübner, Strasbourg 1910 ( p. 129 ).

↑ ^a ^b ^c ^d Franz-Viktor Salomon (Ed.): Textbook of poultry anatomy . Fischer-Verlag, Jena / Stuttgart 1993, ISBN 3-334-60403-9 .

↑ How the colorful variety of bird feathers is created www.farbimpulse.de, the online magazine for color in science and practice

↑ Wilfried Westheide, Reinhard Rieger (Ed.): Special Zoology. Part 2: vertebrates or skulls . Spektrum Akademischer Verlag, Heidelberg / Berlin 2004, ISBN 3-8274-0307-3 , p. 406.

↑ P. Mullen, G. Pohland: Studies on UV reflection in feathers of some 1000 bird species: are UV peaks in feathers correlated with violet-sensitive and ultraviolet-sensitive cones? In: Ibis. 105, 2008, pp. 59-68. doi : 10.1111 / j.1474-919X.2007.00736.x .

↑ Vincent Perrichot, Loïc Marion, Didier Néraudeau, Romain Vullo, Paul Tafforeau: The early evolution of feathers: fossil evidence from Cretaceous amber of France. In: Proc. R. Soc. B. 22 May 2008, vol. 275 no. 1639, pp. 1197-1202. doi: 10.1098 / rspb.2008.0003

↑ Josef H. Reichholf : Natural history {n} - About fit coots, beavers with a migration background and why we want the environment in balance , Knaus , Munich 2011, ISBN 978-3-8135-0378-4

↑ See Gassl Customs: Hahnenfeder and Cutting Feather

↑ Bernd Hoppe, Jürgen Martens : Amino acids - production and extraction. In: Chemistry in Our Time . 1984; 18, pp. 73-86.

↑ Bird feathers are supposed to make aircraft more efficient. www.pressetext.com, April 16, 2009.

[LangsFWPlumology-1] Manfred Eichhorn (Ed.): Langenscheidt specialist dictionary biology English: English - German, German - English . 1st edition. Langenscheidt, Berlin et al. 2005, ISBN 3-86117-228-3 , p. 537 .