Paradisea Rudolphi
The birds-of-paradise are members of the family Paradisaeidae and have about 14 different genera divided in 41 species. Our interest, however, was to study the Blue Bird-of-paradise, (Paradisaea rudolphi) due to some unique particularities in its appearance and behavior.
The species occurs in the eastern Central Ranges of Papua New Guinea and, owing to ongoing habitat loss, limited range, small population size and the hunting for its highly prized plumes, it’s classified as Vulnerable.
The species is approximately 30 cm long, black with an ivory beak, dark brown iris, grey legs, broken white eye-ring and bright blue wings. The male is adorned with violet blue and cinnamon flank plumes and two long ribbon-like tail feathers. The female has a chestnut brown below.
The plumage variation between the sexes (sexual dismorphism) is closely related to the breeding system.
The Blue Bird-of-paradise is best known for the striking beautiful colors of their feathers and the way the male performs an incredible courtship display.
During the mating dance the bird hangs from a branch upside down. The black oval with red margin at the centre of his chest is rhythmically enlarged and contracted. His violet blue plumes spread out in a fan, swaying its body back and forth while the central tail feathers form two impressive arches down to either side. Throughout his performance he vocalizes softly in a low but harsh vibrating voice.
An even more interesting fact about this unique bird is that its feathers reflect the incident light in different directions and are able to generate several colors at the same time.
This is due to multiple thin film or multi-layered melanin reflectors incorporated in the feathers.
Depending on the angle from which the bird is being observed, the feathers reflect completely different colours. During the mating rituals, when the male hangs upside down, from the female’s point of view the feathers are yellow, but when they’re watched from the sides they reflect the colour blue.
The species occurs in the eastern Central Ranges of Papua New Guinea and, owing to ongoing habitat loss, limited range, small population size and the hunting for its highly prized plumes, it’s classified as Vulnerable.
The species is approximately 30 cm long, black with an ivory beak, dark brown iris, grey legs, broken white eye-ring and bright blue wings. The male is adorned with violet blue and cinnamon flank plumes and two long ribbon-like tail feathers. The female has a chestnut brown below.
The plumage variation between the sexes (sexual dismorphism) is closely related to the breeding system.
The Blue Bird-of-paradise is best known for the striking beautiful colors of their feathers and the way the male performs an incredible courtship display.
During the mating dance the bird hangs from a branch upside down. The black oval with red margin at the centre of his chest is rhythmically enlarged and contracted. His violet blue plumes spread out in a fan, swaying its body back and forth while the central tail feathers form two impressive arches down to either side. Throughout his performance he vocalizes softly in a low but harsh vibrating voice.
An even more interesting fact about this unique bird is that its feathers reflect the incident light in different directions and are able to generate several colors at the same time.
This is due to multiple thin film or multi-layered melanin reflectors incorporated in the feathers.
Depending on the angle from which the bird is being observed, the feathers reflect completely different colours. During the mating rituals, when the male hangs upside down, from the female’s point of view the feathers are yellow, but when they’re watched from the sides they reflect the colour blue.
Or when someone suffers from anxiety or depression that causes stress. Since stress causes more pression there it would lead to more pressure inside those heads. And those people tend to search for dark places. What could be an indication that in such environments their pressure lowers and they feel better. Or simply the body, having high pressures, "tries" to escape from it by looking for a place in which it would have a mechanism for lowering it. The person would this way feel tempted unconsciously to go to the dark.
Coming back to our Rudolphi bird, we have tried to demonstrate that if in humans light is probably related with lowering/capacity to endure intracranial blood pressure, it could also happen on it. And thinking about it, the effect must be achieved by a certain wavelenght. Because it´s a certain wavelenght that is reflected by the feathers to the male, and not a random one. Because the feathers have that special capacity of reflecting certain colors (wavelenghts) for certain directions, including the direction that aims for the male's eye.
And now making the backward thinking: what if certain wavelengths stimulated the lowering of pressure inside blood vessels inside the head of humans? Darkness could do it, but what if an intense specific wavelenght did it at a higher scale?
Shall we try to point a intense light to tan eye of an human and check what happens? But maybe not to the eye. The bird curved its head to the feathers direction so that its head could catch the light reflected from the feathers. But the eyes are not the only thing that light reaches.
And before going on, we need to take a look at eye's evolution, in an intending brief way.
Evolution of some structures (such as the eye) can be followed and understood by examination of different species that occupy different positions.
Coming back to our Rudolphi bird, we have tried to demonstrate that if in humans light is probably related with lowering/capacity to endure intracranial blood pressure, it could also happen on it. And thinking about it, the effect must be achieved by a certain wavelenght. Because it´s a certain wavelenght that is reflected by the feathers to the male, and not a random one. Because the feathers have that special capacity of reflecting certain colors (wavelenghts) for certain directions, including the direction that aims for the male's eye.
And now making the backward thinking: what if certain wavelengths stimulated the lowering of pressure inside blood vessels inside the head of humans? Darkness could do it, but what if an intense specific wavelenght did it at a higher scale?
Shall we try to point a intense light to tan eye of an human and check what happens? But maybe not to the eye. The bird curved its head to the feathers direction so that its head could catch the light reflected from the feathers. But the eyes are not the only thing that light reaches.
And before going on, we need to take a look at eye's evolution, in an intending brief way.
Evolution of some structures (such as the eye) can be followed and understood by examination of different species that occupy different positions.
The "eyevolution"
Evolution of some structures (such as the eye) can be followed and
understood by examination of different species that occupy diferent positions
in the "timeline" of
evolution. Fossils of such species constitute a common way of studying such
species, but not very useful in the case of smooth structures such as eyes,
since they are easily decomposed and usually do not fossilize. However, there
are other alternatives to rebuild the sequence of species that presented progressively different eyes.
Among the ones who still exist nowadays, there are different groups of species who present different degrees of complexity of this structure and so it is sometimes possible to order them by such complexity and correlate this order with different stages of evolution.
And in the eye's case we have the following:
Among the ones who still exist nowadays, there are different groups of species who present different degrees of complexity of this structure and so it is sometimes possible to order them by such complexity and correlate this order with different stages of evolution.
And in the eye's case we have the following:
New branches refer to groups of species which today present different
characterists and which are believed evolved in a different way somewhere in
the past.
The complexity of eye goes so this way:
The complexity of eye goes so this way:
We human beings take part of jawed vertebrates, then having an eye with
an only lense (crystallino) and photoreceptors including cones and rots. And
beyond that, we must also refer that we
have a retina subdivided in 3 layers: photoreceptors, bipolar cells and
ganglion cells. And that photoreceptors are the cells that are sensitive to the
light.
All the jawed vertebrates present the same kind of eye, so then
scientists thought of them as descending from a common ancestral A having this
type of eye, which by its way evolved from a specie B, which used to own a
simpler eye.It could be hard to find such specie, but scientists divised that
there it could be more descendants of B, which not A, that instead of evoluting
for a complexer eye like A, went on presenting the charesteristic eye of B. So
that scientists went out to find, among all of those who are vertebrates but not
jawed, one that owned a different eye.. Lamprey, an interesting animal who
lives in water, and, lacking of a proper mouth, sucks its food intead of
bitting it, is a jawless, vertebrate who caught the attention of scientists.
But it already presented an eye looking like our ones. Perseveringly the search
continued. Till a "cousin"of lamprey (also a jawless one and
"almost vertebrate"), a specie called hagfish, was studied.
First it is important to note that hagfish is almost blind, and that
despite it, its eyes didn't disappear along the time. So its eyes must have
some function (that not the vision).
Second, hagfish can be an example of the kind of eye that our eyes evolved from . Beyond what was said, even lamprey, during its growing, in the larva stage, present a retina with 2 layers, no iris or crystalline, no muscle supporting eye and the eye is under the skin (similar to hagfish). Then, during metamorphosis, retina develops a 3 layer (bipolar cells), a crystalline and an iris are formed and eye comes to the surface.
Evolution of eye is then a valid theory. With some errors in the proccess, is said by some scientists, refering to the structure of the layers of retina (in which the one sensitive to the light, photoreceptors, is the last one to be reached by the light which comes from crystallino, having so to pass through all the layers till achieve them).
Second, hagfish can be an example of the kind of eye that our eyes evolved from . Beyond what was said, even lamprey, during its growing, in the larva stage, present a retina with 2 layers, no iris or crystalline, no muscle supporting eye and the eye is under the skin (similar to hagfish). Then, during metamorphosis, retina develops a 3 layer (bipolar cells), a crystalline and an iris are formed and eye comes to the surface.
Evolution of eye is then a valid theory. With some errors in the proccess, is said by some scientists, refering to the structure of the layers of retina (in which the one sensitive to the light, photoreceptors, is the last one to be reached by the light which comes from crystallino, having so to pass through all the layers till achieve them).
Coming back to our theme, we were thinking about pointing an intense
certain wavelenght beam of light and check if it caused a lowering of blood
pression. Then we saw that when bird faced itself, light was reflected into its
eyes, but not only. Then we saw that we could have a a structure of eye which
has evolved from an eye which was used for a function that not seeing.
So, linking everything, what if that fuction was not lost in lhe evolution? This is, what if vision was added to the previous function, rather than substitute them? Vision is the most visible function, but many organs have more than one function, some of then very subtile. So then our eye's structure may perhaps do more than see. Maybe they can, being stimulated with certain wavelengths, generate a lowering in blood pression.
And more, what if the light of certain wavelenght who stimulated the eye structure didn't pass through the crystallino, but instead, was pointed to the region below the eye, where there is a very thin skin?
That skin is extremely thin; it is indeed very hard to find through all the body a region with such thin skin. To let light pass through?
It is placed in a zone where there is no bone. The region above the eye is covered by bone till the eye. Why below not? To let light pass through?
It also must have many and superficial blood vessels and nerves in that region, because we can see the first ones and because it is sensitive (and painful) when we tight it between fingers. Why?
And when we sleep bad, when we are tired, we usually get that region below eye more swoolen and even looks darker or browned. To act as as filter of light to regulate the blood pression that in such circumstances can be higher?
And finally, let´s look at the light pathway, if it reaches that region of skin, rather than crystallino:
So, linking everything, what if that fuction was not lost in lhe evolution? This is, what if vision was added to the previous function, rather than substitute them? Vision is the most visible function, but many organs have more than one function, some of then very subtile. So then our eye's structure may perhaps do more than see. Maybe they can, being stimulated with certain wavelengths, generate a lowering in blood pression.
And more, what if the light of certain wavelenght who stimulated the eye structure didn't pass through the crystallino, but instead, was pointed to the region below the eye, where there is a very thin skin?
That skin is extremely thin; it is indeed very hard to find through all the body a region with such thin skin. To let light pass through?
It is placed in a zone where there is no bone. The region above the eye is covered by bone till the eye. Why below not? To let light pass through?
It also must have many and superficial blood vessels and nerves in that region, because we can see the first ones and because it is sensitive (and painful) when we tight it between fingers. Why?
And when we sleep bad, when we are tired, we usually get that region below eye more swoolen and even looks darker or browned. To act as as filter of light to regulate the blood pression that in such circumstances can be higher?
And finally, let´s look at the light pathway, if it reaches that region of skin, rather than crystallino:
The first layer of retina that light founds is photoreceptors!
So that the position of the 3 layers wouldn't be an error of evolution. It makes sense: if there is 2 functions of eye's structure, vision and the other; if one works with light from crystallino (vision) and the other with light filtred*/that passes through the thin skin; the light which goes from crystallino, focused, used for vision, don´t lose so much intensity(crystallino is transparent) as the one which passes through skin, despite thin. So the light of crystallino "has enough strenght"to goes through the other layers of retina and achieve photoreceptors. For the "weaker" light that has passed skin, the photoreceivers are the first layer achieved. So the order of layers fits perfectly.
And...hagfish has also its eyes covered by skin, what does not blocks the eye's function.
And so light with a certain wavelenght pointed to subeye zone maybe causes a decrease in blood pression.
So the bird of paradise can perhaps lowers it by the certain light reflected from its feathers.
But what if it is not that? Sometimes what makes sense, fits an observation, is not the reason because it happens. Even because there is more explanations that make sense.
For example, bird could as well lowers its pression by producing hormones with that effect. It gets upside down during the nupcial parade. Reproduction is very correlated with hormones.
Even can happens that light reduces blood pression and hormones too. Sometimes separated mechanisms have the same effect. And it could also happens that they are correlated. Light in the skin below eye could perhaps reduce the blood pression by a change in hormones levels or production of one or more.
A way for discovering the role of hormones would be check if there was some one(s) in the birds when upside down that caused lowering of pression. But this birds are indangered and so maybe the study could be taken in other animals that are also under some conditions that favor higher intracranial pressions...
So that the position of the 3 layers wouldn't be an error of evolution. It makes sense: if there is 2 functions of eye's structure, vision and the other; if one works with light from crystallino (vision) and the other with light filtred*/that passes through the thin skin; the light which goes from crystallino, focused, used for vision, don´t lose so much intensity(crystallino is transparent) as the one which passes through skin, despite thin. So the light of crystallino "has enough strenght"to goes through the other layers of retina and achieve photoreceptors. For the "weaker" light that has passed skin, the photoreceivers are the first layer achieved. So the order of layers fits perfectly.
And...hagfish has also its eyes covered by skin, what does not blocks the eye's function.
And so light with a certain wavelenght pointed to subeye zone maybe causes a decrease in blood pression.
So the bird of paradise can perhaps lowers it by the certain light reflected from its feathers.
But what if it is not that? Sometimes what makes sense, fits an observation, is not the reason because it happens. Even because there is more explanations that make sense.
For example, bird could as well lowers its pression by producing hormones with that effect. It gets upside down during the nupcial parade. Reproduction is very correlated with hormones.
Even can happens that light reduces blood pression and hormones too. Sometimes separated mechanisms have the same effect. And it could also happens that they are correlated. Light in the skin below eye could perhaps reduce the blood pression by a change in hormones levels or production of one or more.
A way for discovering the role of hormones would be check if there was some one(s) in the birds when upside down that caused lowering of pression. But this birds are indangered and so maybe the study could be taken in other animals that are also under some conditions that favor higher intracranial pressions...