昨晚睇咗一套非常好的紀錄片Chris Tarrant Extreme Railway Journeys Series 2  Crossing the Andes 安地斯山脈.


在影片開頭,  Chris 介紹了他要去睇 Nitrates Mine, 在19世紀Nitrates又叫white gold, 非常值錢是用來製造 gun powder 的 guano (海鳥屎含豐富的硝酸鹽). 


guano:  The word "guano" originates from the Andean indigenous language Quechua, which refers to any form of dung used as an agricultural fertilizer.
就是裡d 海鳥屎引起了War of Pacific,
https://en.wikipedia.org/wiki/War_of_the_Pacific
自1883年後, 玻利維亞失去出海口，成為內陸國.
 
我知道雀屎都有用的時候, 是我睇咗 Nauru: An Island Country Destroyed by Phosphate Mining:  
http://www.amusingplanet.com/2015/06/nauru-island-country-destroyed-by.html
不過, 佢地叫雀屎為phosphate, 唔係guano.

 

The reasons are:

 

1.  After the Big bang, the energy burnt out, the whole universe cooled down gradually :  The truth is, not only Mars was cooling down, even our Earth is cooling down too.

ref:  no. 1

 

2.  Obviously , Mars is further away from the Sun, and also it is  a lot smaller than the Earth, that is why it is cooling down more quickly.

 

 

 

3. Mars has a lot less green house gas .

ref:  no. 2

 

 

 

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ref:  no. 1

The cosmic background radiation is radiation left over from early development of the universe, and is a landmark proof of the Big Bang theory. Before the formation of stars and planets, the Universe was smaller, much hotter, and filled with a uniform glow from its white-hot fog of hydrogen plasma. As the universe expanded, both the plasma and the radiation filling it grew cooler. When the universe cooled and stable atoms could form, they eventually could no longer absorb the thermal radiation and the universe became transparent instead of being an opaque fog. The photons that from that time have been propagating ever since, growing fainter and less energetic. The CMBR has a thermal black body spectrum at a temperature of 2.725 K, so it peaks in the microwave range frequency of 160.2 Ghz(1.9 mm wavelength).

 

http://www.universetoday.com/79777/cosmic-background-radiation/

https://nightsky.jpl.nasa.gov/news-display.cfm?News_ID=631

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ref:  no. 2

scientists believe, Mars must have lost its most precious asset: its thick atmosphere of carbon dioxide. CO₂ in Mars's atmosphere is a greenhouse gas, just as it is in our own atmosphere. A thick blanket of CO₂ and other greenhouse gases would have provided the warmer temperatures and greater atmospheric pressure required to keep liquid water from freezing solid or boiling away.

http://science.nasa.gov/science-news/science-at-nasa/2009/06nov_maven/

To understand how the core of Mars has formed, we need to look at how the whole solar system did come to be, the inner, rocky planets like Earth and Mars and the outer, gas giants like Jupiter and Saturn.  The picture below does show the whole history of the formation of our galaxy the Milky Way and our solar system.

 

 

Here is a picture zoomed in at our solar system as it is now.

 

 

And here is the theory of how our planets have formed:

 

https://youtu.be/0zAAIYMDsTo

 

 

Our solar system, consists of:

The inner, the Rocky, or Terrestrial planets  :   Mercury, Venus, Earth and Mars.   

The outer planets, the Gassy Giants:  Jupiter, Saturn, Uranus and Neptune.

How the rocky planets formed:

1.  The material that formed our solar system originates probably from a supernova explosion somewhere in our Milky Way. It formed a cloud that collapsed due to gravity and started to spin and as it spun it slowly flattened out to form a disk. Astronomers call such a disk a protoplanetary disk or short a proplyd, and as it collapsed it got hotter and hotter until fusion occurred and our sun was born. About 99.9% of all the material in the proplyd went into the sun, the 0.1% of the proplyd’s leftovers formed the rest of the solar system, the planets and planetoids.

2. The intense heat of the young sun drove away gassy materials (a lot of hydrogen and helium) from the inner parts of the solar system.  Making this region deprived of hydrogen and helium and formed the outer planets, the gassy planets Jupiter, Saturn, Uranus and Neptune. These gas giants contain 99% of the leftover material, so what we're left with is a tiny residue of a tiny residue to form the inner rocky planets, including our Earth.

3. Closer to the sun, from that tiny residue of a residue, you find material orbiting, orbiting in the inner orbits, and that material is less gassy. There's more sort of solid stuff. You have little dust motes that eventually will gather together through electrostatic forces or collisions to form little rocks. You have particles of ice that will eventually form snowball-like objects, and eventually they form things like meteorites or asteroids, and they're getting bigger and bigger and bigger and they're colliding with each other. And in each orbit, you eventually get large objects that finally sweep up through their gravitational pull, everything else that's in the orbit. And so, eventually, over a hundred million years, in each orbit you have a rocky planet. Now, this process is called accretion.

 

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Since the four rocky planets were created with the same process there structure is very similar and varies only due to their different sizes , their distance from the sun and the time lapsed since their creation.

 

 

Very little is known about the core of Mars, but we can project the probability of the structure of its core from the knowledge we have gained about the Earth’s core.

 

https://youtu.be/ZzcXGqrvxJc

 

 

The early earth was extremely hot for a number of reasons :  

1. Radioactivity:  The supernova that blew up just before the solar system was formed created a huge amount of radioactive material, the radioactivity generated a lot of the heat. 

2. Accretion: The violent collisions of materials like meteorites and asteroids in the early Earth created huge amounts of heat.

3. Pressure: As the clouds of dust from the supernova became denser and denser due to gravity, an enormous amount of heat was generated particularly at the centre where the highest pressure occurred. 

In fact, the early Earth did get so hot that it melted, and that is really important. Because if it hadn't melted, today's Earth would be very different from the way it is.  To get a sense of what happened and why this was so important, let's imagine a kind of absurd cooking experiment. 

 

Put some stuff in a sauce pan. You're going to put in some coins. You're going to put in some rice. You're going to put in some plastic. Let's add a bit of mud. 

Let's put in some ice and you can chuck in one or two other things.  And now, we're going to heat that stuff up to several thousand degrees. Don't stir, just let it simmer. 

Finally, what we'll see is that the whole thing is going to melt.  The heavy stuff, such as the coins, are going to sink down to the bottom, lighter stuff is going to rise to the top, and some stuff is going to evaporate and boil above the sauce pan. 

 

Now something very like this seems to have happened to the early Earth.  It melted and because it melted, it formed a series of layers and they give it the structure we have today. Let's look at the four main layers. 

 

 

1. The Inner and the Outer Core :   The first is at the centre and is mainly iron and nickel because they are heavier than most other materials and therefore sank to the centre of the Earth.  And the fact that the centre of the Earth is full of magnetic metals (iron and nickel) is really important because this gave the Earth its magnetic field, and the magnetic field deflects some of the sun's rays that would be harmful to living creatures such as us.  So that's the first layer, the core. 

 

2. The Mantle : The lighter stuff-- lighter rocks-- float above the core and form a layer that's called a mantle.  Now, the mantle you can think of as a sort of hot sludge of rocks.  These rocks are so hot they're sort of semi-molten and they're actually moving around in convection currents inside the mantle. 

 

3. The Crust : At the very top, we have a layer called the crust.  Very light rocks such as basalts and granites stayed on the top, they cooled down and formed a thin solid layer, the crust.  That's where we live.  The crust is pushed around by the convection currents from underneath.  You can think of the crust as a tiny, thin layer a bit like a sort of egg shell. 

 

4.  The Atmosphere : Finally, the fourth layer, the atmosphere.  Some of the gassy stuff bubbles up to the top, it evaporates.   The very light gases such as hydrogen disperse into space, but a lot of other gases like Nitrogen and Oxygen, just hang around the Earth held by its gravitational pull.

 

And that's how the Earth acquired the structure it has today.  All of this happened about ten million years after the creation of our solar system.

 

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https://youtu.be/XNkArWUT8pA

A new animation by NASA scientists illustrates what Mars – the fourth planet from the Sun and the second smallest planet in the Solar System – may have looked like billions of years ago.

Billions of years ago when the Red Planet was young, it appears to have had a thick atmosphere that was warm enough to support oceans of liquid water - a critical ingredient for life. The animation shows how the surface of Mars might have appeared during this ancient clement period, beginning with a flyover of a Martian lake. The artist's concept is based on evidence that Mars was once very different. Rapidly moving clouds suggest the passage of time, and the shift from a warm and wet to a cold and dry climate is shown as the animation progresses. The lakes dry up, while the atmosphere gradually transitions from earth-like, blue skies to the dusty pink and tan hues seen on Mars today.

Today, Mars is a cold, desert world. Liquid water cannot exist pervasively on its surface due to the low atmospheric pressure and surface temperature, although there is evidence for spurts of liquid flow that perhaps consist of a briny solution with reduced freezing temperature. Water under current conditions can be ice or sublimate directly into vapour without staying in a liquid phase.

Now a day, scientists are not yet certain if the core of Mars is solid, liquid, or in two distinct sublayers, like Earth.  Future measurements will tell us more.

 

http://mars.nasa.gov/allaboutmars/facts/

 

We learn from our science class during our secondary school that Mars is a red planet, and it is red, because it is full of rusty iron on the surface of the planet.

I just watch the follow video, and found it very interesting:

https://youtu.be/7koIlNPay-s

The iron got rusty because of the rain/water and the oxygen in the air, causing the iron oxidized.

But if you look closely at the surface of Mars, you’ll see that it can actually be many different colours. Some regions appear bright orange, whilst others look more brown or even black. But if you average everything out, you get Mars’ familiar red colour.

What  I am most  curios about Mars is:

If I could stand on the surface of Mars and look around, is

 

1.the sky on Mars  red too?

(The dust in the atmosphere scatters the red photons, makes the sky appear red. We have something similar when there’s pollution or smoke in the air.)

2. the sunsets blue?

(The dust absorbs and deflects the red light, so you see more of the blue photons streaming from the Sun.) 

https://youtu.be/tc2ctrrLHso

 

Further…………so,  Mars is further away from the sun than the earth, I wonder how bright is daylight on Mars?

ANSWER from Jim Murphy on July 18, 1997:
The brightness of the sun on Mars, were there to be a clear day, is about
half the brightness of a similar day here on Earth.  I arrive at the value
of one-half simply by knowing that the brightness of an object decreases by
the square of the distance, and since mars is on average 1.5 times as far
from the Sun as earth, 1.5 times 1.5 is 2.25, and 1 divided by 2.25 is 0.44,
or 44 percent as bright.

Now, just because the apparent brightness is half, that does not necessarily
mean that the scene will be half as bright on Mars.  Mars' less massive
atmosphere will mean less scattering of light, and thus the clear martian
sky would not be as blue as here on earth, and all the scattered light which
we see here on Earth, which makes the sun appear a bit less of a flashlight
beam than it is would all conspire to make the Martian sky appear darker.

 

http://quest.arc.nasa.gov/mars/ask/atmosphere/Brightness_of_daylight_on_Mars.txt

Experiment 1.  Misconceptions about falling objects , YouTube channel, Veritasium:

Dr Derek Muller takes to the streets with a 5kg medicine ball (exercise ball or fitness ball) and a 1 kg basketball and poses the question:
when dropped from the same height, which one will hit the ground first? You may know the correct answer, but can you explain why?



According of what Dr. Derek Muller’s explanation: the force on the medicine ball is greater than the force on the basketball, but it has more inertia and what's really important is that the ratio of force to inertia is the same for all objects, so everything accelerates at the same rate and lands at the same time.

Let’s have a look at another experiment from Brian Cox:

Experiment 2.  Feathers and bowling ball:
In this experiment, a bowling ball and feathers are dropped in the air of the atmosphere, and then again in a vacuum. The result...might not surprise you since you learned what would happen in secondary school science class.




P.S.  :  the same experiment was done by Apollo 15 Hammer and Feather Drop (Aug., 1971):



So, why does the basket ball and the medicine ball take the same time to hit the ground?  they are in air, not in a vacuum chamber!  
How can you explain why the feather and the bowling ball in Brain Cox’s experiment do not arrive at the same time, when the experiment conducted in air?
The force on the bowling ball is greater than the force on the feather, but the bowling ball has more inertia, so that the ratio of force to inertia is the same for all objects, and everything accelerates at the same rate and lands at the same time.  But the fact is, in air, the feather falls much slower than the bowling ball due to the air resistance. The air resistance on the feather is much greater than the air resistance on the ball.

What is wrong on the Dr. Derek Muller’s experiment??   It seems everything he said is correct! 

Comparing these two videos, we find:

Dr. Muller’s experiment :  the medicine ball and the basket ball, their size and shape is exactly the same.  Professional Brian Cox’s experiment:  the feathers and the bowling ball, their size and shape is different, so they have a different air resistance! 
The reason why Dr. Muller is using the same size balls for his experiment is because they have the same air resistance , so he doesn’t need to do the experiment in a vacuum chamber to prove that gravity is a constant at a given place on earth.

Let us use now Newton’s second law to calculate the velocity in the Dr. Derek Muller’s experiment:
http://en.wikipedia.org/wiki/Gravity_of_Earth



F = Force [N] Newtons,   m = mass [kg] kilo grams,  a = acceleration [m/s²] meter / second²

basket ball :
F = 1kg x 10 m/s²    ( actually, it should be  9.81 metres (32.2 ft) per second every second, for simplicity, we use 10 instead of 9.81) 
F = 10 Newtons.

medicine ball :
F = 5kg x 10 m/s²  
F = 50 Newtons.

because : a = F / m

basket ball:
a    = 10 Newtons / 1kg   =  10 kg * m / kg *  s²  = 10 m/s²    

a    = 50 Newtons / 5kg   =  50 kg * m / kg *  s²  = 10 m/s²    

That is the proof that the acceleration of earth is constant !  The gravitational constant.  (check this out :  http://en.wikipedia.org/wiki/Gravitational_constant  )

----------------------------------------------------------------------------------------------------------------
Experiment 3:  a 15 kg dumbbell and a  25 kg dumbbell :




And now, we are sure that:
A 15 kg dumbbell and a 25kg dumbbell will accelerates at the same rate and lands at the same time, when they are being dropped in a vacuum room.
But how about if we make a  dumbbell with 15kg that has exactly the same shape and size as the 25kg dumbbell would it also land at the same time if we drop them in air?
The answer is conditional, if we would manage to keep both dumbbells exactly aligned with each other during the fall then they would have the same air resistance and consequently land at the same time. But if the dumbbells are out of alignment with each other, during the fall, one could have more air resistance than the other and consequently they do not land at the same time.
This does not come into it in the experiments with the balls because the ball shape is homogeneous and thus the air resistance is not affected by the rotational alignment of the balls,  the same does not apply to the dumbbells!

Further more, it is worth to mention that the earth acceleration has the dimension [m/s²], it is only a force when we multiply it with a mass [kg], [m/s² * kg = N] N stands for Newton which is a force. So we can talk about all forces of the universe, which are measured in Newton.
We have 4 forces in the Universe:
1. The electro magnetic force
2. The weak nuclear force
3. The strong nuclear force
    We know all about these three forces but not all about the fourth force.
4. The gravitational force : we know how big it is ( very very small) and we know all about its behaves, but we do not know what it is, as yet. 
    But there is some hope that with the discovery of the Higgs Boson (they call it the god particle) we will be able to explain gravity.

What is gravity? :


As you can see, most of the people will answer that it is a downward force that stops you from flying away from the earth.  Or a force that pulls all matter together.  The more matter, the greater the gravitational attracting force, so the things that have a lot of matter such as planets and moons and stars have a lot of attraction force. 
We all learned these answers in the secondary school, so we just need to remember it!  
But fact is that even science still cannot explain what the gravitational force is!
They know how it behaves and they know how big it is, but they still don’t know what it is! 

We know that every massive object falls to the ground and we know this is because of gravity.

But back in time of Aristotle the scientific opinion was that the speed at which an objects falls was directly related to their relative weights. Thus, a heavy object would fall faster than a lighter object.  After all, pick up a feather and a rock and drop the two of them, and Aristotle’s view will be prove,

the rock will indeed fall faster than feather.

As mentioned before, the gravitational force pulls all forces together.  In the examples of dropping balls, feathers and dumbbells onto the ground we have ignored the movement of the earth. But since the mass of the earth is so massive as compared with our dropping items used in the experiments, we can ignore the earths movement, it is immeasurable small. Nevertheless if the falling objects getting larger, like the size of the moon for example then the movement of the earth is detectable which is shown in the following video.


.

If an object with comparable mass to that of the Earth were to fall towards it, then the corresponding acceleration of the Earth would be observable.

 

 

Nearly 10 years ago, I had moved to Australia.  My new neighbour Ron called me to see him close to his fence in our backyard.   Ron lived behind our house and he used to be a famer, he grew vegetables and loved to check us out, he wanted to know what we are doing. 

When I walked closer, he said : “Mei, do you know that the red back spider is poison and deadly?”  I told him that I did not know that and  I did never see one yet! 

Then he pointed his finger to the fence just between both of us, and then I saw a spider with a red point on the black who was hanging in a tiny web.  I screamed immediately.   Ron laughed and put his finger on top of the spider and squashed it, he killed the spider.  He told me this is a piece of cake, he kills red blacks all the time.

After then, I did kill one myself when we renovated our backyard.  I was moving a brick which has 6 holes in the middle, a red black did hide in one of this holes, when I moved it, I saw a red back spider moving, it was already close to my finger,  I was scared and dropped the brick onto the floor, the spider was thrown out and fell onto the floor, I immediately stepped on it.  

Then I knew red back spiders are not aggressive, just don’t wait until they bite you, you will be fine.

 

當我初來澳洲住, 我家後花園有個老鬼鄰居, 常常關注我家的動靜.

有天他見我在後園種花. 他叫我走到圍欄去聊天.

並問我道: 你可知否悉尼紅背蜘蛛是惡毒無比嗎?

我剛來報導, 當然對那些小動物是沒什興趣的, 當他知道我一無所知..... 就開始陰陰咀笑.... 

佢用手指一指角落, 說: 看, 那隻就是啦! 

我看到一隻細小黑蜘蛛, 背部圓圓上是有一小紅點.  動也不動, 掛在蛛網上.

隨著, 老鬼便用手指往蜘蛛上一擠壓,  我"嘩"一聲,  老鬼覺得好不威風.  他說他殺紅背蜘蛛當食生菜.

後來, 我家後園重修, 我自己也看到過不少紅背蜘蛛, 也自己殺死過一隻. 

當時是好害怕的, 它就是躲在一磚頭裡,  當我移動磚頭時發現了它, 立即就嚇到掉到地上,  它也被拋出掉在地上, 我好自然就往它身上踩去.  

依我所見, 紅背蜘蛛根本不活躍的, 不是網上說的會向你攻擊的.  它們行動不快, 你有足夠時間殺鬼死它們, 肯定快過它們襲擊你.

 

Red Back Spider - Attenborough: Life in the Undergrowth – BBC

 

 

 

Red Back Spider - toilet spider

 

http://en.wikipedia.org/wiki/Redback_spider

紅背蜘蛛是一種劇毒蜘蛛，身長在2—8mm之間，背部有個紅色印記，攻擊性極強，被咬中五分鐘後傷口開始發熱發痛，如無血清治療，半小時內死亡。但自1956年以來，並無記錄在案的因紅背蜘蛛咬傷而死亡的案例。

紅背蜘蛛偏好棲息於黑暗乾燥處，雌性紅背蜘蛛會在交配後，把消化液注入雄蜘蛛的身體和把雄蜘蛛吃掉。據研究發現，母紅背蜘蛛壽命有2-3年；公蜘蛛壽命只有6-7個月，有83%的雄性紅背蜘蛛在沒有交配之前就死掉了。

有趣:

1.  紅背蜘蛛網:  晚上建築, 並且是三維建築的, 不單是和橫濶, 而是向下向深.  (睇BBC, attenborough – Life the Undergrowth 就是.) 只要你想像天上就是一般的蜘蛛網, 可是他從網中一些線向下再築更多的支線接觸著地面或平面.  當有小動物經過觸摸到, 就被纏著整隻獵物被彈起.  因為彈起在半空, 而沒有了其中東西可以被依靠, 紅背蜘蛛就可以爬下來把你用網絲包起來, 慢慢吸食.

2.  紅背蜘蛛 原來是外來客. 不是原產澳洲! (睇片: Red Back Spider - toilet spider)

 

Referring to the top 10 cute animals – earth unplugged
http://youtu.be/MepHOlXh-w0

Now, I would love to have a look on the no. 5 cute animal - the Owl that Ms. Maddle mentioned on her above video:

 

1. Owls belong to the Order Strigiformes (鴞形目).
The Order Strigiformes is further divided into two families, the barn owls (Family Tytonidae) and the typical owls (Family Strigidae). Owls are a diverse group of birds, with over 220 species of owls belonging to the Order Strigiformes.

 

 

 

有趣:

1. A. 貓頭鷹有兩大家族: the barn 糧倉owls (Family Tytonidae) , and the typical 典型 / True owls (Family Strigidae).

     B. 點解會叫: 糧倉貓頭鷹?  原來這種貓頭鷹喜歡在糧倉閣樓建巢.

http://www.owlpages.com/owls.php?genus=Tyto&species=alba

These pale, nearly worldwide birds are closely associated with man through their traditional use of barn lofts and church steeples as nesting sites

然而, 牠們的學名Tyto alba卻是白貓頭鷹 : Tyto是希臘文的貓頭鷹. alba是拉丁文的白.

http://en.wikipedia.org/wiki/Barn_owl

The barn owl's scientific name, established by G.A. Scopoli in 1769, literally means "white owl", from the onomatopoetic Ancient Greek tyto (τυτο) for an owl – compare English "hooter" – and Latin alba, "white"

 

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http://twistedsifter.com/2010/08/10-facts-about-owls/

 

2.  The structure of an owl’s foot is referred to as zygodactyl (攀木頖鳥, 腳掌前後有雙趾的).
This means that two of the toes face forward while two face backward. This arrangement enables the owls to capture and grasp prey with greater ease. Sometimes, the third toe can be rotated forward into a position occasionally used for perching棲息.

 

http://en.wikipedia.org/wiki/Owl

Talons爪

While the auditory and visual capabilities of the owl allow it to locate and pursue its prey, the talons and beak of the owl do the final work. The owl kills its prey by using these talons to crush the skull and knead the body.^[16] The crushing power of an owl’s talons varies according to prey size and type, and by the size of the owl. Theburrowing owl (Athene cunicularia), a small partly insectivorous owl, has a release force of only 5 N. The larger barn owl (Tyto alba) needs a force of 30 N to release its prey, and one of the largest owls, the great horned owl (Bubo virginianus) needs a force of over 130 N to release prey in its talons.^[20] An owl’s talons, like those of most birds of prey, can seem massive in comparison to the body size outside of flight. The masked owl has some of the proportionally longest talons of any bird of prey; they appear enormous in comparison to the body when fully extended to grasp prey.^[21] An owl’s claws are sharp and curved. The family Tytonidae have inner and central toes of about equal length, while the family Strigidae have an inner toe that is distinctly shorter than the central one.^[20] These different morphologies allow efficiency in capturing prey specific to the different environments they inhabit.

 

 

有趣:

2.  A. 牠們爪部有4腳趾. 兩前兩後. 方便牠們獵食時的急速捕捉食物的. 第3趾是可以轉向前, 來抓住樹幹停留, 當如有需要時.

      B. 牠們的爪是非常強而有力的, 比較細小的貓頭鷹, 你要用5N ( N=newtons, m = w/g = (5 N) / (9.81 m/s²) = 0.50 kg 去打開牠的爪來奪取牠的食物.  大一點如barn owl 就要30 N 了, 就是3.1kg的力.  再大到如horned owl, 就要超過130N, 13公斤的力了.  貓頭鷹一定要有咁大力才可用爪來壓碎獵物的頭腦捏圓或扁獵物的身體.

      C. 牠們的趾甲也非常銳利和彎曲.

 

3. Owls are birds of prey(食肉烏).
Owls feed on a wide variety of prey including mammals, other birds, insects, and reptiles. There are even some species of owls that live in Africa and Asia that feed on birds. Owls cannot chew their prey since, like all birds, they do not have teeth. Instead, they swallow small prey whole and must tear larger prey into smaller pieces before swallowing. They later regurgitate pellets of indigestible material such as bone, fur, and feathers.

 

    

 

有趣:

3. A. 貓頭鷹的食物包括: 哺乳動物, 鳥, 昆蟲, 魚和爬虫類等等, 因為貓頭鷹跟鳥類一樣, 牠們是沒有牙齒的, 所以牠們必須先用爪將食物撕碎成細塊吞食,  並且稍後會反芻那些難消化食物, 如骨, 羽毛和毛革等等. 

 

4. Owls’ eyes are fixed in their sockets (眼窩).

http://www.owlpages.com/articles.php?section=owl+physiology&title=vision

Of all an Owl's features, perhaps the most striking is its eyes. Large and forward facing, they may account for one to five percent of the Owl's body weight, depending on species. The forward facing aspect of the eyes that give an Owl its "wise" appearance, also give it a wide range of "binocular" vision(seeing an object with both eyes at the same time). This means the owl can see objects in 3 dimensions (height, width, and depth), and can judge distances in a similar way to humans. The field of view for an owl is about 110 degrees, with about 70 degrees being binocular vision.

 

 

有趣: 

4.  A. 貓頭鷹的眼睛是不能轉動的, 是固定在眼窩. 

     B.  貓頭鷹眼睛之大, 是佔牠體重1-5%.

     C.  兩眼睛是可以同時望到同一物件在三維 (高, 寬和深), 並且可以立即猜測到物件的距離.

     D.  上圖:  貓頭鷹兩眼睛共看到110度 the view angle (左眼20度, 右眼20度,  兩眼向前有70度, 共110度) , 人類的眼界範圍是180度 (左眼20度, 右眼20度,  兩眼向前有140度, 共180度).  然而烏類的雙眼睛卻可一齊向前看, 又可分別單獨看.  在 birdnote.org  烏類的眼是3倍更銳利清晰過人類.  因為各眼在頭的兩邊, 他們可以一齊看, 又可分別看, 所以當然是360度全看了.  

          All birds have the fascinating ability to see in what is termed binocular and monocular vision. This simply means birds eyes work together as a pair to see straight ahead, but each eye can also see independently of the other eye. This monocular vision is the reason for the varying placement of the eyes on different bird species.

For instance, the pigeon has eyes on the side of its head. This placement gives them the amazing capability of seeing almost everywhere around them. The only place they can't see is directly behind them. The American woodcock's eyes are situated closer to the top of the head and can therefore see what's behind it! This bird can still see what is in front and above the head as well.

http://voices.yahoo.com/the-fascinating-eyesight-birds-357295.html?cat=70

http://birdnote.org/show/birds-eye-view-i

http://birdnote.org/show/birds-eye-view-ii

 

By comparison, humans have a field of view that covers 180 degrees, with 140 degrees being binocular. A woodcock has an amazing 360 degree field of view, because its eyes are on the side of its head. However, less than 10 degrees of this is binocular.

An Owl's eyes are large in order to improve their efficiency, especially under low light conditions. In fact, the eyes are so well developed, that they are not eye balls as such, but elongated tubes. They are held in place by bony structures in the skull called Sclerotic rings. For this reason, an Owl cannot "roll" or move its eyes - that is, it can only look straight ahead!
The Owl more than makes up for this by being able to turn its head up to 270 degrees left or right from the forward facing position, and almost upside down ( barn-owl can turn its head 180 degrees). There are several adaptations that allow this, outlined in the Owl Skeletal system article.

 

有趣:

4. E. 貓頭鷹的眼睛是不能轉動並且固定在眼窩上, 要能在黑夜出動捕食, 牠的頭部必須作出配合了,   所以牠頭部不單左右轉動270度, 還可正面上下轉180度.

 

 

As most owls are active at night, their eyes must be very efficient at collecting and processing light. This starts with a large cornea 眼角膜(the transparent outer coating of the eye) and pupil (the opening at the centre of the eye). The pupil's size is controlled by the iris 虹膜(the coloured membrane suspended between the cornea and lens). When the pupil is larger, more light passes through the lens and onto the large retina 視網膜(light sensitive tissue on which the image is formed).
The retina of an owl's eye has an abundance of light-sensitive, rod-shaped cells appropriately called "rod" cells. Although these cells are very sensitive to light and movement, they do not react well to colour. Cells that do react to colour are called "cone" cells (shaped like a cone), and an Owl's eye possesses few of these, so most Owls see in limited colour or in monochrome.
Since Owls have extraordinary night vision, it is often thought that they are blind in strong light. This is not true, because their pupils have a wide range of adjustment, allowing the right amount of light to strike the retina. Some species of Owls can actually see better than humans in bright light.

To protect their eyes, Owls are equipped with 3 eyelids. They have a normal upper and lower eyelid, the upper closing when the owl blinks, and the lower closing up when the Owl is asleep. The third eyelid is called a nictitating 眨眼 membrane薄膜, and is a thin layer of tissue that closes diagonally across the eye, from the inside to the outside. This cleans and protects the surface of the eye.

 

有趣:

4. F. 貓頭鷹的眼睛結構如上圖,  因為晚間捕食, 所以眼睛必須對光有效率地收集和處理.  貓頭鷹對眼有一種"rod"細胞, 對光和移動物件都非常敏感, 可是這種細胞卻對顏色卻反應較差, 於是大部分的貓頭鷹都是睇到極有限的顏色, 甚至只是單色圖而已.

     G. 貓頭鷹有3片眼簾. 上眼簾閉上時, 是當貓頭鷹眨眼.  下眼簾閉上時, 是當貓頭鷹在睡覺.  第3片眼簾  對角線地閉上 (看以下片段, 便知道, 第3片眼簾是隱藏在眼角, 當要清潔眼睛表面時, 便會很快的向眼尾掃去.   貓頭鷹片段可能不太明顯, 大家可看看大象的片段, 第3片眼簾的動作是一樣的.)

 

  

 

 

5. Owls' head turning ability  貓頭鷹頭部可以270度轉動的原因:

 

 

http://www.owlpages.com/articles.php?section=Owl+Physiology&title=Skeleton#headturn

 

An Owl's skeleton is typical for birds. Designed for both walking and flying, it is very light and strong. In owls, the skeleton makes up about 7-9% of its total body weight. Many of the bones which would be separated in mammals are fused together in birds, making them strong to support their weight on the ground. In addition, some of the larger bones are hollow, with bony internal bracing. This helps reduce overall weight.

Several Owl species have obviously asymmetrical 不對稱skulls, which is an adaptation to for directional hearing.

Owls' head turning ability

An owl can turn its head up to 270 degrees left or right from the forward facing position. An owl cannot turn it's head full circle from a forward facing position as is the common belief. There are several adaptations that allow this:
1) An owl's neck has 14 vertebrae, which is twice as many as humans.
2) Owls have only one occipital articulation with the cervical vertebrae. (There is only one bone situated on top of the backbone.) Humans have two articulations. This allows the owl to pivot on the vertebrae column much like your body can pivot on one foot. Their muscle structure is arranged in a manner that allows this movement as well.
3) Owls have a special arrangement of the jugular veins (靜脈)with associated bypass connector blood vessels, to ensure that blood supply (and return) are not impeded as the neck is rotated.

The large flat breastbone, or Sternum, supports the large and powerful flight muscles. It also protects the heart, lungs and other internal organs. In the Tytonidae family of owls, the Carina, or Sternum Keel is broad, becoming narrower towards the abdomen, and the lower edge of the sternum has only small notches on each side. In the family Strigidae, the carina is narrow at its upper part, and becomes broader towards the belly, while the lower edge of the sternum has two deep notches on each side.

The wing bones are relatively long in owls, and the associated wing surface area is broad, producing a low wing loading. This allows for easy take-offs, and effortless flight, even when carrying prey.

The foot bones, or tarso-metatarsi, are relatively short and stout in owls, most likely to aid in the efficient killing and carrying of prey.

 

http://www.hopkinsmedicine.org/news/media/releases/owl_mystery_unraveled_scientists_explain_how_bird_can_rotate_its_head_without_cutting_off_blood_supply_to_brain

The most striking team finding came after researchers injected dye into the owls' arteries(動脈) , mimicking blood flow, and manually turned the animals' heads. Blood vessels at the base of the head, just under the jaw bone, kept getting larger and larger, as more of the dye entered, and before the fluid pooled in reservoirs. This contrasted starkly with human anatomical ability, where arteries generally tend to get smaller and smaller, and do not balloon as they branch out.
Researchers say these contractile blood reservoirs act as a trade-off, allowing owls to pool blood to meet the energy needs of their large brains and eyes, while they rotate their heads. The supporting vascular network, with its many interconnections and adaptations, helps minimize any interruption in blood flow.
"Our in-depth study of owl anatomy resolves one of the many interesting neurovascular medical mysteries of how owls have adapted to handle extreme head rotations," says de Kok-Mercado, now a scientific illustrator and animator at the Howard Hughes Medical Institute.
Moreover, says Gailloud, "our new study results show precisely what morphological adaptations are needed to handle such head gyrations and why humans are so vulnerable to osteopathic injury from chiropractic therapy. Extreme manipulations of the human head are really dangerous because we lack so many of the vessel-protecting features seen in owls."
The first anatomical variation they discovered was in the owl neck, where one of the major arteries feeding the brain passes through bony holes in the vertebrae. The hollow cavities were approximately 10 times larger in diameter than the vertebral artery traveling through it. The researchers say the extra space in the transverse foraminae, as the holes surrounding the vertebral arteries are known, creates a set of cushioning air pockets that allow the artery to move around when twisted. Twelve of the 14 cervical vertebrae in the owl's neck were found to have this adaptation.
"In humans, the vertebral artery really hugs the hollow cavities in the neck. But this is not the case in owls, whose structures are specially adapted to allow for greater arterial flexibility and movement," says de Kok-Mercado.
The team also found that the owl's vertebral artery enters the neck higher up than in other birds - going in at the owl's 12th cervical vertebrae instead of the owl's 14th cervical vertebrae - allowing for more vessel room and slack.
Among de Kok-Mercado and Gailloud's other findings were small vessel connections between the carotid (頸動物)  and vertebral arteries - not usually seen in adult humans - that allow blood to be exchanged between the two blood vessels. The researchers say these so-called anastomoses, including a vessel connection called a patent trigeminal artery, allow for uninterrupted blood flow to the brain, even if one route is blocked during extreme neck rotation.

 

貓頭鷹頭部可以270度轉動的原因:

有趣:

5. A.  貓頭鷹頸部有14塊椎骨, 比人類多出一倍.

     B.  貓頭鷹頸部只有一塊枕骨與頸椎骨連接, 情況就如人類膝蓋(如下圖) 後, 轉動角度就大好多了,  但人類的頸枕骨卻是兩片連一起,來支持我們的頭部, 也是妨礙了頭部可轉動更大的角度.

     C.  貓頭鷹頸部下巴的動脈會在頭部轉動時,  圑聚大量血液 ( 血管腫脹起來) 來應付牠頭部在轉動時, 腦部, 眼睛等等的力量來源.

     D.  横切面的椎間孔的直徑是頸部椎骨動脈的直徑的十倍大. 而動脈受到周圍的氣囊所包圍, 就像墊一樣的保護著. 使得貓頭鷹頭部轉動時而不受到損害.   貓頭鷹14塊頸部椎骨就有12塊是這種結構.  人類的動脈卻縛緊在頸椎骨的空洞內.

     E.  貓頭鷹頸動脈是比起其它鳥類,  早兩節椎骨離開頸椎骨(即14節椎骨,  動脈就在第12節離開) 後接上頭部, 使得頭部更有空間和鬆動可以轉來轉去. 

 

 

6. Hearing 聽力:

  http://www.owlpages.com/articles.php?section=owl+physiology&title=hearing

Because Owls are generally active at night, they have a highly developed auditory (hearing) system. The ears are located at the sides of the head, behind the eyes, and are covered by the feathers of the facial disc. The "Ear Tufts" visible on some species are not ears at all, but simply display feathers.

The shape of the ear opening (known as the aperture) depends on the species of Owl - in some species, the opening has a valve瓣膜, called an operculum 鰓蓋covering it . The opening varies from a small, round aperture to an oblong slit with a large operculum. All owls of the family Tytonidae have rounded openings with large opercula, while in Strigidae, the shape of the outer ear is more varied.

An Owl's range of audible sounds is not unlike that of humans, but an Owl's hearing is much more acute at certain frequencies enabling it to hear even the slightest movement of their prey in leaves or undergrowth.

Some Owl species have asymmetrically 不對稱地set ear openings (i.e. one ear is higher than the other) - in particular the strictly nocturnal species, such as the Barn Owl or the Tengmalm's (Boreal) Owl. These species have a very pronounced facial disc, which acts like a "radar dish", guiding sounds into the ear openings. The shape of the disc can be altered at will, using special facial muscles. Also, an Owl's bill 鳥嘴is pointed downward, increasing the surface area over which the soundwaves are collected by the facial disc. In 4 species (Ural, Great Gray, Boreal/Tengmalm's & Saw-whet), the ear asymmetry is actually in the temporal parts of the skull, giving it a "lop-sided" 不平衡的appearance.

An Owl uses these unique, sensitive ears to locate prey by listening for prey movements through ground cover such as leaves, foliage, or even snow. When a noise is heard, the Owl is able to tell its direction because of the minute time difference in which the sound is perceived in the left and right ear - for example, if the sound was to the left of the Owl, the left ear would hear it before the right ear. The Owl then turns it's head so the sound arrives at both ears simultaneously - then it knows the prey is right in front of it. Owls can detect a left/right time difference of about 0.00003 seconds (30 millionths of a second!)

An Owl can also tell if the sound is higher or lower by using the asymmetrical or uneven Ear openings. In a Barn Owl, the left ear left opening is higher than the right - so a sound coming from below the Owl's line of sight will be louder in the right ear.

The translation of left, right, up and down signals are combined instantly in the Owl's brain, and create a mental image of the space where the sound source is located. Studies of Owl brains have revealed that the medulla (the area in the brain associated with hearing) is much more complex than in other birds. A Barn Owl's medulla is estimated to have at least 95,000 neurons 神經元- three times as many as a Crow烏鴉.

Once the Owl has determined the direction of its next victim, it will fly toward it, keeping its head in line with the direction of the last sound the prey made. If the prey moves, the Owl is able to make corrections mid flight. When about 60 cm (24") from the prey, the Owl will bring its feet forward and spread its talons in an oval pattern, and, just before striking, will thrust it's legs out in front of it's face and often close it's eyes before the kill.

http://video.nationalgeographic.com/video/worlds-deadliest-ngs/deadliest-owl

 

對於要在黑夜獵食的貓頭鷹, 除了視力和爪力外, 聽力也不能缺少:

有趣:

6. A. 貓頭鷹耳朵的構造是奇特的,  是在頭部的左右兩邊, 一上一下, 位置並不對稱的. 好處就是可以收集不同方位的聲音.  舉例:  當聲音來自左邊, 左邊耳先收到音訊, 貓頭鷹便轉動頭部, 當聲音是同步到達雙耳,  即是說獵物就在正中前面了.   在0.00003 秒間, 貓頭鷹就可以在0.00003 seconds (30 millionths of a second!)立即洞察到這左到右的聲音來源, 而立即分析到獵物方向.

6. B. 同樣是跟以上解說有相同的道理,  因為左耳高, 右耳低, 於是當聲音來自視線之下時, 右耳一定大聲過左耳了.   因此貓頭鷹可以立即分析到獵物方向.

6. C.  所有這些聲音來源經過左右耳至到大腦的 medulla, 在medulla 有最少95,000神經元, 比烏鴉多出3倍.

6. D.  另外, 除了以上所說外,  貓頭鷹臉大如一雷達天線碟般, 加上臉部肌肉的動作等, 能收集聲源進入耳朵.

 

 

 

7. Flight and feathers  飛行和羽毛

 http://www.owlpages.com/articles.php?section=owl+physiology&title=Feathers

 

 

 

Birds have up to five feather types:
1. Contour feathers cover the body, wing (remiges) and tail (rectrices).
2. Down feathers -  these soft and fluffy feathers trap air and create a layer of insulation next to the bird's body.
3. Semiplumes function to fill in between contour and down feathers.
4. Bristles are small feathers with a stiff shaft and barbs only on the base, or often not at all. Bristles occur most commonly around the base of the bill, around the eyes, and as eyelashes.
5. Filoplumes are hairlike feathers that consist of a very fine shaft with a few short barbs at the end. They are typically covered by other feathers, and may function as pressure and vibration receptors - they sense the location of other feathers so they can be adjusted properly.

An Owl has very few down feathers, but has downy barbules on the parts of the contour feathers closest to the skin.
Many of the Owl's feathers are specially designed - around the face there are the stiff facial disc feathers or ruff, crown feathers, ear-flap feathers and also bristles around the bill.

The feet and bill have Filoplumes that work somewhat like feelers觸鬚, to help the Owl react to things they touch, such as prey.

The most unique adaptation of Owl feathers is the comb-like or fimbriate (fringe-like) leading edge of the primary wing feathers referred to as "flutings" 刻凹槽or "fimbriae"毛缘. With a normal bird in flight, air rushes over the surface of the wing, creating turbulence湍流, which makes a gushing noise. With an Owl's wing, the comb-like feather edge breaks down the turbulence into little groups called micro-turbulences. This effectively muffles压抑 the sound of the air rushing over the wing surface and allows the Owl to fly silently. There is also an alternate theory that the flutings actually shift the sound energy created by the wingbeats to a higher frequency spectrum辐射源, where most creatures (including prey and humans) cannot hear.

Silent flight gives Owls the ability to capture prey by stealth, and also allows the Owl to use its hearing to locate potential prey. This adaptation is not present on some Owl species that hunt in the daytime.

 

好了,  貓頭鷹聽到獵物所在, 當然就必須趕緊飛去捉住獵物, 這樣就必須要提到牠的羽毛如何幫助牠飛行了.

有趣:

7. A.  貓頭鷹有5種不同的羽毛, 功能除了1. 保暖外, 牠羽毛特別的梳邊和刻凹槽結構是可以 2. 抑壓飛行時發出聲音.   並且 3. 在腳上和在它嘴邊毛就跟觸鬚般敏銳, 當他們捉到獵物時使牠們可以反應非常快.

7. B.  另一學說, 牠羽毛特別的梳邊和刻凹槽結構是可以改變了由翼拍動時發出聲音的音頻,  使得音頻高出牠獵物或人類可以聽到的音頻.

   

8. Pattern and Colour  圖樣和顏色

In general, an Owl's cryptic colours and pattern allow it to blend in with its surroundings, hiding it from potential danger. This is especially important for the nocturnal owls, as they need to remain hidden when roosting in the daytime.
When threatened, an owl will often take up a concealing posture, with closed eyes, raised ear tufts, and compacted feathers.
The ear tufts are actually nothing to do with hearing, they are display feathers, used to indicate moods, such as fear, anger and excitement. They also help with camouflage偽裝. It is also interesting to note that although owls of the same species look alike, each individual owl within a species has slightly different markings.

 

 

貓頭鷹的羽毛的圖樣和顏色都是有保護的功用.

有趣:

8. A. 看上圖就知道, 貓頭鷹的羽毛的圖樣和顏色是可以完全隱藏在背景之中的.

8. B. ear tufts  原來跟聽覺無關的.  它是用來表達心情的, 是恐懼, 是憤怒, 又或是興奮.  並且也可以用來偽裝.  因為當受嚇的時候, 貓頭鷹會立即開始隱藏自己在背景中, 它敝上一對大眼, ear tufts 升起, 所有羽毛壓緊.

 

9. Preening 用嘴整理羽毛

All birds frequently clean and groom their feathers in order to remove dust, dirt and parasites寄生物.  Owls, like most other birds, use their beak and talons to do this. The two outer talons on the owls feet are the "feather combs". The sharp medial edge of these outer talons enables them to clean their heads.
Flight feather barbs倒钩  have tiny barbules 魚鬚 that lock the barbs together, making the feather into a single continuous surface. These barbules often become unhooked during harsh粗糙的 flying conditions or collisions碰撞. A bird will use its beak to realign 重新排列the unhooked barbs and restore the feather to peak 最頂condition.
There is small gland called the uropygial, located at the base of the tail, that produces a thin oily liquid. This gland is stimulated by the beak, which is then used to transfer the liquid to the feathers to provide them with a protective coating.

 

有趣:

9. A. 貓頭鷹尾的底部有一細小乳腺, 用來分泌薄薄的油液, 由嘴巴刺激而分泌, 再由嘴巴 preening 時, 將油液擦到羽毛上去, 成為一層保護膜.

9. B. 貓頭鷹整理羽毛時的動作和形態, 是跟小鳥大致一樣的.

 

 

Boreal Owl Preening in Forest -Raw footage from Dale Bohlke on Vimeo.

 

10. Molting  換毛

When an Owl hatches孵化, it has no flight feathers, but is covered with downy feathers that keep it warm. This down is gradually replaced with feathers as the Owl grows. Juvenile 年青時 plumage 羽衣is similar to adult's, but often paler, and sometimes with different markings.

An adult bird's colour is derived from mature feathers. During the normal course of the bird's life, these feathers suffer from damage caused by abrasion, flexing and even collisions.
Like other birds, Owls regularly replace their feathers in a process known as molting. This usually happens once a year, beginning after the parent birds have raised a brood 孵蛋 that has fledged 長羽毛and can care for themselves.
The process takes up to 3 months, during which feathers are shed 脱落and re-grown over the entire body in a regular pattern. In order to minimise the impact of the molt on the Owl's flight and hunting skills, this molting pattern only allows a few of the primary or secondary flight feathers to be shed at time.
With the exception of the Barn Owl, molting of wing feathers is from the inside out. Barn Owl wing feathers are replaced from the middle of the wing out (in both directions). Tail feathers also drop out a few at a time, except in some smaller Owl species, who loose all the tail feathers at once.

When birds molt, new feathers grow to replace the ones that have fallen out. The new feathers immerge from the skin tightly bound in a thin shaft of tissue. These are called pin feathers. The shaft splits shortly after, allowing the new feather to unfurl 張開and grow to its full size.

 

11. Flight 飛行

Most owls have relatively large, rounded wings. The wings are broad, with a large surface area relative to the weight of the bird i.e. a low wing loading. This allows them to fly buoyantly and effortlessly, without too much flapping and loss of energy. They can glide easily and fly slowly for long periods of time. Many species use this slow flight to hunt ground-dwelling prey from the air.

 

 

12. Owls create a variety of vocalizations.  多種類發聲法
Owls create a wide variety of sounds or vocalizations. The familiar hoot is usually a territorial declaration, though not all species are able to hoot. Other sounds owls might make include screeches, hisses, and screams.

 

13.  Most owls are nocturnal. 夜間活動
Most owls are active at night. A few species (such as the pygmy owls) are active in the early morning or at dusk while some (such as the burrowing owl and the short-eared owl) are active during the day.

 

14. Owls are found in all regions of the Earth except Antarctica, most of Greenland and some remote islands.

 

 

 

Further more:

What does a Barn Owl sound like?

http://www.mirror.co.uk/news/weird-news/looking-right-twit-owl-turns-1861289

http://voices.yahoo.com/the-fascinating-eyesight-birds-357295.html?cat=70

 

 

 

For the number 10, The Snow Leopard, I did write a blog as following:
http://meiwechner2099.blogspot.com.au/2014/05/snow-leopards-purr.html

For the number 9, The Clown fish , I did write a blog as following:
http://meiwechner2099.blogspot.com.au/2014/05/clown-fish_17.html

 

For the number 8, The Chipmunk , I did write a blog as following:

http://mei-mei-wechner.blogspot.com.au/2014/05/chipmunk.html

For the number 7, The pygmy leaf chameleon , I did write a blog as following:

http://mei-mei-wechner.blogspot.com.au/2014/05/pygmy-leaf-chameleon-bearded-leaf.html

 

For the number 6, The Red Panda , I did write a blog as following:

http://meiwechner2099.blogspot.com.au/2014/05/red-panda.html?view=magazine