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Polar Bears - Data, Pictures and Videos

India sanjay Offline
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Question: How much milk do polar bear cubs drink?

Answer(Dr. Thea Bechshoft) :

good question (and one that took me to new nooks and crannies of the polar bear literature!).

Healthy polar bear cubs increase massively in weight from the day they are born (500-800 gram) to the day they emerge with their mother from the maternity den (10-12 kg). This rapid weight gain comes from the cubs drinking their mother’s milk. Polar bear milk is the fattiest of any bears’. It contains about 40% fat when the cubs first start nursing, and decreases to around 20% as the cubs grow older. The fat percentage and the quality of the milk is of course also dependent on the mother’s body condition – the less body fat she has, the less fat she will be able to pass on to the cubs through her milk.

Although quite a few studies have looked into the quality and composition of polar bear milk, only one group of researchers have looked at the amount of milk consumed by polar bear cubs: in their study published in 1990, the researchers Arnould and Ramsay estimated that polar bear cubs in Western Hudson Bay during the ice-free period consumed 469 gram milk/day for cubs of the year (those under 1 year of age) and 131 gram milk/day for yearlings (those over one year old, but still with their mother and still nursing). Another way you could try to get this question answered would be to contact a zoo that has had to hand-raise a polar bear cub. Although the milk formula used for hand rearing the cubs has a somewhat different composition than actual polar bear mother’s milk, it should still give you an indication of how much the cubs consume.

I've found two videos for you: a polar bear nursing her single 2-3 month old cub (https://www.youtube.com/watch?v=MN2crSgz4PM) and a polar bear nursing her almost 2 year old twin cubs (https://www.youtube.com/watch?v=Ijq0qmH_Q9I). The cubs will often make a sound called trilling when nursing or simply well fed and happy - have a listen here: https://www.youtube.com/watch?v=FrPpj0MXB-s. Finally, for comparison: human babies drink about 750 ml (= approx. 750 gram) milk per day during their first 6 months (there is of course a huge variation - as mentioned, this is an average). However, human breast milk is only about 4% fat, meaning that human babies may drink more milk, but polar bear cubs have a much higher energy intake per serving.
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Sanju Offline
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thanks @sanjay
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United States Pckts Offline
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Venezuela epaiva Offline
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( This post was last modified: 04-20-2019, 02:41 AM by epaiva )

Polar Bear skull it measures 42 cent long
Credit to @natural_selections

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Sanju Offline
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Female
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Luipaard Offline
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First-ever video of wolf and polar bear interaction!




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India sanjay Offline
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Good short doucmentry from NGC




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Finland Shadow Offline
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( This post was last modified: 07-23-2019, 01:59 PM by Shadow )

How to break a coconut? We have tools, gorillas use rocks to hit and break coconut or hit coconut against rock... here is how "big boys" do it Wink Even though this one is called Ewa and is beautiful female polar bear, her companion, big male Wilbär is most probably sleeping somewhere nearby :) He did the same earlier.





Often we see bite force estimations in different studies and how people argue about it, that which animal has more or less and often differences are in reality meaningless. I think, that if this polar bear could speak and someone would ask, that how strong your bite is, answer would be simple: Strong enough!
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India sanjay Offline
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Arctic is no place for cute




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Australia GreenGrolar Offline
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Polar Bear Fur Isn’t (Technically) White – It’s Translucent!


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Curious polar bears at Bernard Spit, AK. Image: Steven Kazlowski/ Barcroft Media


I doubt there is anyone reading this who when confronted with the question: “what color is polar bear fur?” wouldn’t respond “white.”  It certainly looks white and yes, for all intents and purposes, polar bear fur is white.  But perhaps you’ve noticed that sometimes a polar bear looks yellow, gray, or even green.
Why is that?  Do some polar bears have different color coats?  Does the coat color of a polar bear change with the environment?  Do polar bears just need better shampoo?  Before we get to the bottom of why polar bears appear to have such a range of colors, it’s important to know a key fact about polar bear fur.  Polar bear fur isn’t technically white…it’s translucent.
That’s right, a polar bear’s outer coat consists of guard hairs that are actually devoid of pigment and are essentially “clear” hollow tubes.

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Polar Bear at Bernard Spit, Alaska. Image: Steven Kazlowski/ Barcroft Media


Now I’m sure you want to know how it is that a polar appears white (and yellow, green, etc.) with all that translucent fur, so let’s talk about the structure of hair.  Mammalian hair is composed of keratin which is typically organized into three layers.
The cuticle is the outermost layer and is comprised of a very thin, translucent layer of overlapping “scales.”  Below the cuticle is the cortex which consisted of long, spindle-shaped cells and may contain pigment granules (in the case of colored hair) along with corticle fusi (which are essentially air spaces).  Lastly, in certain hairs of some animals, an additional layer known as the medulla is also present.  The medulla is essentially a structured, air-filled core that is quite well-expressed in many arctic animals such as polar bears.
In the case of a polar bear, the guard hairs consist of a thin cuticle encasing a well-developed cortex and a wide medulla.  Since the cortex in these hairs is devoid of pigment and the medulla is essentially a wide airspace, light that bombards the polar bear’s fur is scattered in all directions giving the appearance of a white bear.  So when you see a polar bear and perceive it as a big, cuddly mass of white fluff, you’re eyes are actually interpreting the scattering of all wavelengths of visible light rather than a color produced by pigments.


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Polar bear guard hair under scanning electron microscopy. Source: Nano Nature.


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Polar bear guard hair (400x). The medulla appears black under transmitted visible light. Source: Alaska State Museum.

So what about the sometimes gray, yellow, or green appearance of these bears?  In the case of gray bears, the color is most likely the result of the thinner coat produced by polar bears in the summer.
Since polar bears have black skin, a little bit of the black undertone can show through the thinner summer coat and produce a gray appearance.  This is particularly evident around the face of a polar bear near the nose.
In the case of yellow bears, it would seem that prolonged exposure to sunlight oxidizes the hair strands, creating a yellow appearance.  Thus, a polar bear appears whitest after a fresh molt when the hair is freshest.
Last, but not least, is the curious case of the greenish polar bears.  Greenish polar bears are often seen in zoos located in warm climates and in 1979, researchers Ralph Lewin and Phillip Robinson determined that the greenish appearance is the result of algae.  Under warm conditions, the “hollow” medulla of polar bear guard hairs creates a humid microclimate that is well-suited for fostering masses of green algae derived from the enclosure ponds of these captive bears.
Since the rest of the hair is translucent, the green color from the algae in the medulla shows-through and creates a greenish appearance.  However, I should note that this phenomenon appears to be restricted only to the guard hairs since the medulla of undercoat fibers appear to be too thin (in the area of a 20 micrometers) to facilitate algal infiltration and growth.

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Polar bear fur with algae growth.


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Source: Higashiyama Zoo, Japan, 2008.
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Polar bear fur with algae growth. Source: Higashiyama Zoo, Japan, 2008.
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Polar bear fur with algae growth. Source: Higashiyama Zoo, Japan, 2008.
So there you have it: polar bears fur isn’t really white at all.  Now go take this new-found knowledge and blow some minds.
Further Reading
  • Derocher, A. E. and W. Lynch 2012. Polar Bears: A Complete Guide to Their Biology and Behavior. Johns Hopkins University Press, Baltimore, Maryland
  • Lewin, Ralph A., and Phillip T. Robinson. “The greening of polar bears in zoos.” (1979): 445-447.
  • Microscopy of Hair Part II: A Practical Guide and Manual for Animal Hairs. 2004. Federal Bureau of Investigation, Quantico, Virginia.
  • IUCN/SSC Polar Bear Specialist Group
  • Alaska State Museum Bulletin.  Issue 45.
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Australia GreenGrolar Offline
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The Biggest Myth About Polar Bear Fur (And the Weirdest Truth).






The humble polar bear has one interesting quirk to its fur, which has netted it two different problems. One is algae, and one is a piece of pseudoscientific nonsense.



In the YouTube video above, you're going to see a couple of green bears. This is actually pretty common among zoo bears, especially in hot and muggy climates. It's not just that algae grows on their hair. It's that algae grows inside their hair. While most animals produce hair that's a long, thin cable, polar bears produce hair that's a hollow tube - like the world's most dangerous drinking straw. The tube is colorless, but it's made with translucent material. Any light that comes in is scattered, and so it appears white. (This is one of the reasons polar bears look brightest in direct sunlight.) In cold or harsh climates, the tube of hair stays empty. In hotter ones, even if the bear is being regularly washed, algae starts growing inside the tube of hair, turning large sections of the bear green.





In the 1970s, people noticed the similarities between bear hair and fiber optic cables. They also noticed that a shaved polar bear has black skin. Suddenly people thought that they had discovered how the bears stayed warm. Their hair was channeling heat right to their skin, which was absorbing it as only black material can. It was a great notion, nature going high tech, but sadly it was shown to be false. Finally, Daniel Koon, a researcher at St. Lawrence University tested out the notion.

It was thoroughly debunked. The the hair channeled between a thousandth and a trillionth of a percent of visible light for one inch, and it absorbed UV light entirely. Biologists pointed out that being the perfect fiber optic cable might not work well for bears. They're already built to withstand the cold, but being on an exposed piece of ice in all-day sun with no shade, night, or relief would cause them to overheat. You can still find the myth in plenty of places, though.
Via Applied Optics, Alaska Science Forum, Bear.org, and The Library of Congress.
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Australia GreenGrolar Offline
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( This post was last modified: 09-12-2019, 10:16 AM by GreenGrolar )


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Circulating on Facebook today is a photo (above) of 530-kg Inuka, a polar bear at the Singapore Zoo covered in algae.



https://mothership.sg/2014/06/is-the-algae-growing-on-polar-bear-at-spore-zoo-due-to-recent-hot-weather/

Personally I don't believe that polar bears should be in zoos or captivity as they are one of the least adaptable animals to climate change.
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Australia GreenGrolar Offline
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Polar bears aren't actually white, and sometimes they can turn green.


Polar bears aren't actually white. Their color is determined by the lighting and climate of their surroundings. Following is a transcript of the video.



Polar bears aren't actually white.Turns out, they can come in all sorts of colors: yellow, gray, orange, and even green. That's because polar bear fur is transparent and hollow.When light strikes the outer fur some of it is absorbed while the rest is scattered away.



The result? The fur can appear as different colors under different lighting. Normally, polar bears look white. That's because their fur is scattering sunlight, which is also white. But on a cloudy day, the bears can look slightly gray. At sunset, they can appear reddish-orange. But lighting is only half the story.



Polar bears in zoos have been known to turn green. Concrete floors in their pens scrape against the fur. The abrasions form tiny holes in their hairs, opening a gateway for algae that can live and breed inside. In the Arctic, temperatures are too cold for these algae. But wild polar bear fur can still change color to yellow, thanks to oils from their prey that stain the fur.



Perhaps the most surprising thing about polar bears? Underneath all that hair, polar bear skin is actually black. The black skin readily absorbs sunlight to keep the bear warm. Polar bears aren't just the ambassadors of the North Pole. They're masters at manipulating color to survive.

https://www.businessinsider.com/what-color-is-polar-bear-fur-2017-12/?r=AU&IR=T

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Australia GreenGrolar Offline
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( This post was last modified: 09-13-2019, 07:35 PM by GreenGrolar )


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https://www.tapatalk.com/groups/wildanimalwarfare/who-wins-in-a-fight-between-a-lion-and-a-tiger-t74-s1540.html

Credited to Pablo1111

This is the reason why I do not agree that polar bears should be in zoos, captivity, or circuses.
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