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Post by Gorilla king on Jul 15, 2021 6:31:24 GMT -5
The polar bears with rating 5 are probably pregnant females. If i understood the study good, there were no pregnant females, at least pregnant females were not mentioned anywhere.
Here is the explanation from the study:
1. General appearance emaciated, vertebral processes, ribs, and hip bones externally visible without palpation, no fat palpable between skin and muscle over the dorsal body, hips, or lower rump where last reserves are normally present (Fig. 2)
2. Bear appears thin, vertebral processes and hip bones (but not ribs) partially visible but easily palpable under the skin, little or no fat between skin and muscle over the back but small amounts of fat detectable on lower rump;
3. Bear has healthy appearance, vertebral processes or hip bones not visible but upper third to half of the spinal column can be felt under the skin, detectable layer of fat between skin and muscle over rear half of body, thickening slightly but detectably over lower rump;
4. Bear appears fat, vertebral processes and hip bones not visible, palpation reveals fat deposited over upper vertebral processes, hip bones difficult to feel through fat, fat thick over rump, a hand rubbed back and forth on the lower back above the rump will initiate ripples in the skin over the fat layer;
5. Bear appears obese, vertebral processes and hip bones undetectable by palpation and thick layer of fat is apparent between skin and muscle two-thirds of the way up the back and especially over the rump, a hand rubbed back and forth on the lower back above the rump sets off waves of rolling fat, may appear to jiggle.
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Post by oldindigosilverback on Jul 15, 2021 6:31:25 GMT -5
My mistake. However, a fat bear is still a healthy bear. No records of polar bear’s dying because of obesity.
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Post by Gorilla king on Jul 15, 2021 6:38:17 GMT -5
My mistake. However, a fat bear is still a healthy bear. No records of polar bear’s dying because of obesity. Exactly, no records. Polar bears in relatively bad condition have ratings 1 and 2. The best conditions are ratings 3 and 4. Now take a look at the adult males in autumn:
Total 1125
Rating 1-16 Rating 2-122 Rating 3-733 Rating 4-245 Rating 5-9
Most are rating 3 which is the best, its a healthy looking bear.
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Post by oldindigosilverback on Aug 3, 2021 19:53:09 GMT -5
Polar Bear Fur Is Completely See Through.You may not believe it but Polar bear fur is actually completely see-through, though this doesn’t mean they will be green if they stand on a green lawn. They will appear white because of the way light scatters when reflecting off their transparent fur. Okay we lied, they do sometimes look green! But only because when it gets really too hot, polar bears have been known to stick green algae on themselves to keep cool. Ask anyone what color a polar bear is and they will probably quickly reply that they are white. However, the truth is that their fur is transparent and has no color at all. They appear to be white to the naked eye because their fur reflects the visible light. Due to their transparent fur, if you were to try to take a photo of a polar bear in infrared light then they would barely show up at all. Though perhaps the most surprising thing is that their skin color is actually black. To creatures and humans that can only see visible light, polar bears are the perfect predator that is able to blend in almost perfectly into their environment. However, one mammal has evolved to deal with this situation: deer have a visual system that can outsmart the polar bear’s tricky fur. Deer can actually see in ultraviolet light which allows them to see polar bears extremely easily when they appear on top of an icy white backdrop. When you see a polar bear at the zoo you may be mistaken for thinking they are yellow or green, but this is due to dirt and age. Or unfortunately, in humid and hot temperatures where polar bears are not native, they sometimes start to see algae growing on their skin. And it can also depend on their diet, for example, when they eat a lot of seals then their fur can start to turn yellow due to the seal’s oil. insidetonight.com/polar-bear-fur-is-completely-see-through/
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Post by Gorilla king on Aug 7, 2021 9:19:16 GMT -5
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Post by tyrannosaurs on Aug 8, 2021 6:59:25 GMT -5
From the chapter on Adaptations: photos.app.goo.gl/VyPZ6BZgYtZve4kg8Analyses of key genes involved in Arctic adaptation in polar bears suggest selection on both standing variation and de novo mutations played an important role: Abstract Background Polar bears are uniquely adapted to an Arctic existence. Since their relatively recent divergence from their closest living relative, brown bears, less than 500,000 years ago, the species has evolved an array of novel traits suited to its Arctic lifestyle. Previous studies sought to uncover the genomic underpinnings of these unique characteristics, and disclosed the genes showing the strongest signal of positive selection in the polar bear lineage. Here, we survey a comprehensive dataset of 109 polar bear and 33 brown bear genomes to investigate the genomic variants within these top genes present in each species. Specifically, we investigate whether fixed homozygous variants in polar bears derived from selection on standing variation in the ancestral gene pool or on de novo mutation in the polar bear lineage. bmcgenomics.biomedcentral.com/articles/10.1186/s12864-020-06940-0From polar bear international: photos.app.goo.gl/a6yagdwRyDom6Fut5
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Post by arctozilla on Aug 8, 2021 9:53:33 GMT -5
The polar bears with rating 5 are probably pregnant females. That's what I think too.
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Post by tyrannosaurs on Aug 22, 2021 15:31:16 GMT -5
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Post by oldindigosilverback on Sept 18, 2021 9:15:36 GMT -5
Do polar bears have strong teeth? They are designed to allow the Polar Bear a way to easily dig and to scoop the ice. Polar Bears have a mouth full of 42 extremely sharp teeth. Since they are carnivorous, they need them to kill their prey as well as to consume it. Their teeth are longer and sharper than those of the Brown Bear. www.polarbear-world.com/polar-bear-anatomy/
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Post by oldindigosilverback on Sept 18, 2021 9:22:26 GMT -5
Body Type. Polar bears have a heavy stout body with strong muscular legs and well-developed neck muscles. Compared to other bears, the head of a polar bear is proportionally smaller. The necks of polar bears are longer than their nearest kin, the brown bear. This adaptation makes it easier for them to keep their heads above water when swimming. They have short, fur covered ears and a very short tail. Polar bears have large paws compared to body size, reaching 30 cm (12 in.) in diameter. The large paws of a polar bear act like snowshoes, spreading out the bear's weight as it moves over ice and snow. The forepaws are round, and the hind paws are elongated. The partial webbing between their toes, polar bears are able to use their front feet much like paddles to propel them rapidly through the water. The hind feet are slightly smaller. On both the front and hind feet, the bottoms are covered with dense fur, which affords better traction when moving on ice. Each toe has a thick, curved, nonretractable claw. The claws are used for grasping prey and for traction when running or climbing on ice. The sole of a polar bear's foot has thick, black pads covered with small, soft papillae (dermal bumps). The papillae create friction between the foot and ice to prevent slippage. Long hairs growing between pads and toes also help prevent slippage. Polar bears walk in a plantigrade manner (i.e., in a manner similar to humans with both heel and toe make contact with the ground when walking). On land, they are not as quick as brown bears and appear to have traded off speed for their extremely massive forelegs which they use to break through seal dens or flip a large seal out of the water. They are able to attain speeds of 40 kilometers per hour (25 miles per hour) for short distances. myweb.facstaff.wwu.edu/~brilla/PBear.htm
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Post by oldindigosilverback on Sept 18, 2021 9:27:53 GMT -5
Hibernation
Hibernating means to pass the winter in a dormant or lethargic state. Animals that hibernate store body fat when food is plentiful. When food is scarce, they hibernate, living off their stored body fat. Polar bears do not enter deep hibernation. Deep hibernation applies to an animal whose body temperature drops to 5C (41F) for a period of days or weeks. Deep hibernators also show a marked drop in heart rate, and are slow to wake up when disturbed. Only pregnant female polar bears hibernate. Polar bears are not deep hibernators, but enter a state of carnivore lethargy. Though hibernating females sleep soundly, they are easily and quickly aroused. The female polar bear's heart rate slows to about (8-12 bpm at a low) 27 beats per minute from a normal resting heart rate of about 46 beats per minute.When hibernating, a female's body temperature may drop slightly, perhaps to 35C (95F), or it may remain normal at 37C (98.6F). Unlike many other animals who hibernate, its body temperature only undergoes a minor reduction of 3 to 7 degrees Centigrade (5 to 9 degrees Fahrenheit). Its metabolism slows down by half. Unlike most other hibernators, female polar bears give birth while hibernating. High body temperature is needed to meet the demands of pregnancy, birth, and nursing. Researchers have found that nonhibernating polar bears, during times of food scarcity, can efficiently utilize their energy reserves much like hibernating bears. During the period of hibernation, the polar bear will neither pass urea or solid fecal waste. While urea poisoning causing death would occur in all other animals within a week, bears have developed a unique process of recycling the urea into usable proteins. During the hibernation period, all bears lose a great deal of weight. It is not uncommon for a female polar bear with newborn cubs to lose as much as 40% of her weight. myweb.facstaff.wwu.edu/~brilla/PBear.htmJudging from the sentence underline, it shows that polar bears with 50% fat are pregnant females.
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Post by Gorilla king on Sept 18, 2021 10:48:02 GMT -5
Reply #30, very nice find mate. This line is also very important to show how bears are superior to most other animals morphologically speaking:
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Post by Gorilla king on Oct 4, 2021 5:42:02 GMT -5
GREAT BEAR ALMANAC BY GARY BROWN:
POLAR BEARS MAY HAVE THE MOST SPECIALIZED EYES, PROVIDING VERY ADAPTABLE AND EXCELLENT VISION THAT EXCEEDS THAT OF OTHER SPECIES OF BEARS.
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Post by oldindigosilverback on Oct 4, 2021 6:16:39 GMT -5
A full time predator needs the best eyesight and that is what the yellowish white bear is.
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Post by oldindigosilverback on Oct 14, 2021 10:03:02 GMT -5
Reply #34, you posted that same report as the very first post of this thread mate. My bad. Will try to be more careful. Anyway, this is your post on the Domain:
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Post by oldindigosilverback on Oct 14, 2021 10:08:23 GMT -5
Except for Oldfield et al (2012), the other studies posted here all used the 2D dry skull methods and thus they're not considered to be reliable by modern standards.
Even Oldfield et al (2012) has some issues regarding inconsistencies of their specimens measurements and body mass estimations. Thus, their conclusions may be a bit questionable.
Also, calling out the Polar bears for being a 'weak fat-suckers' while over-hyping Agriotherium as the ultimate apex predator is a bit of a stretch. In reality, it seems to be the opposite. Polar bears have been documented taking on absolutely huge preys. On the other hand, Agriotherium has forelimbs un-suited for grappling, Canines' root surface area are also small which suggests the Canines are not adapted for restraining struggling preys. Read this paper:
"Results show that in absolute terms, canine and carnassial bite forces, as well as root surface areas were highest in A. africanum. However, when adjusted for skull size, A. africanum’s canine roots were smaller than those of extant solitary predators. With teeth being the limiting factor in the masticatory system, low canine root surface areas suggest that A. africanum would have struggled to bring down large vertebrate prey. Its adjusted carnassial root sizes were found to be smaller than those of extant hard object feeders and the most carnivorous tough object feeders, but larger than those of extant omnivorous ursids and Ursus maritimus. This and the fact that it displayed its highest postcanine root surface areas in the carnassial region (rather than the most distal tooth in the tooth row) suggest that A. africanum consumed more vertebrate tissue than extant omnivorous ursids. With an apparent inability to routinely bring down large prey or to consume mechanically demanding skeletal elements, its focus was most likely on tough tissue, which it acquired by actively scavenging the carcasses of freshly dead/freshly killed animals. "
Tooth Root Morphology in the Early Pliocene African Bear Agriotherium africanum (Mammalia, Carnivora, Ursidae) and its Implications for Feeding Ecology
Verdugo posted this account on Carnivora.
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Post by Gorilla king on Oct 14, 2021 10:17:25 GMT -5
One of the most knowledgeable and reliable posters in my opinion.
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Post by Gorilla king on Nov 19, 2021 22:23:58 GMT -5
Musculoskeletal system of the neck of the polar bear (Ursus maritimus) and the Malayan bear (Helarctos malayanus)
Abstract
The gross anatomical study was undertaken in the musculoskeletal system of the neck of the polar bear, and the findings were compared with those of the Malayan bear. The Musculus splenius and the M. trapezius were well-developed in the polar bear. The long neck of the polar bear consisted mainly of the M. splenius with the M. biventer cervicis and the M. complexus lying tightly underneath. The cervical vertebrae possessed huge ventral tubercle in the ventral part of the transverse process in the polar bear. These morphological characteristics suggest that the polar bear may rotate and bend the skull and the long cervical vertebrae. We postulate that the polar bear has evolved the high-mobility long neck to adapt for swimming. Unlike the polar bear, the Malayan bear has not specialized in the neck structure.
www.researchgate.net/publication/12124241_Musculoskeletal_system_of_the_neck_of_the_polar_bear_Ursus_maritimus_and_the_Malayan_bear_Helarctos_malayanus
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Post by Gorilla king on Nov 26, 2021 14:50:56 GMT -5
GREAT BEAR ALMANAC BY GARY BROWN:
EYEWITNESS DESCRIBING A BLIND POLAR BEAR DEMONSTRATES THAT GOOD VISION MAY NOT ALWAYS BE NECESSARY. EVEN THOUGH THE BEAR WAS BLIND, HE WAS STILL FAT, INDICATING THAT HE HUNTED SUCCESSFULLY, USING ONLY HIS HEARING AND SMELLING SENSES.
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Post by oldindigosilverback on Mar 12, 2022 5:31:12 GMT -5
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