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// The Etruscan Bear (Ursus etruscus) // The polar bear evolved from the brown bear and the brown bear is thought to have evolved from Ursus etruscus//.// This bear was similar in size to the brown bear and lived in many different environments. Polar bear The polar bear (//Ursus maritimus)// is the world’s largest land carnivore as well as the world’s largest bear. The polar bear is classified as a vulnerable species. For years they were hunted by indigenous people and by people looking to skin them and take the bears fur. This caused concern for the international community but after strict rules and regulations were put in place, Polar bear populations are on the rise.

__Habitat__: For evolution to occur, there must be some environmental pressures placed on the animal by its habitat. The Polar bear changes habitat slightly as the seasons change. When possible, the polar bear can be found on offshore pack ice or along the coasts of the arctic area. When it heats up during the summer and spring and the ice melts, the polar bears retreat to ice that will stay frozen all year round, this usually means further inland.These seasonal changes are a minor inconvenience for the Polar Bear. During the winter the Polar Bear can be found all over the arctic, most commonly near where seals frequent.

It’s Scientific name translates to “maritime bear”, This is because they have been found swimming up to 320 kilometers from the nearest ice pack, they are extremely strong swimmers and have adapted this way because of the habitat they live in. They can also be found on drifting pieces of ice that place them close to their favorite food, seal. Polar bears overheat quickly so it is hard for them to catch terrestrial prey, however they do sometimes prey on reindeer, birds, rodents and crabs. They have also been documented subduing walrus’s and beluga whales, both of these animals are up to twice the polar bears weight and it is very rare for the polar bear to attempt to catch one of these.

Living in the harsh habitat of the arctic, the polar bear cannot get the amount of calories it needs to survive from hunting land animals. A seal’s blubber is rich in calories and provides the bear sufficient intake to survive. Developing polar bears have been seen eating the protein rich meat of the seal whereas adults have been seen eating mainly the fat or blubber of the seal.Some other animals that live in the arctic are :The seal ( []), The Walrus ( [] ) and the Arctic Fox ( [] )

Polar bears have learned to use this unforgiving environment to their advantage. They are enormously strong and use this strength to help them ambush seals. Seals have “breathing holes” (holes in the ice that allow the seal to come out of the water and breathe before diving back to hunt) the polar bear lies in wait to the side of the breathing hole, when a seal emerges the bear reaches into the whole and drags the seal onto the ice, it then kills it by crushing its skull with its powerful jaw.

Adaptations: 1: This is only possible because the bear has been forced to adapt. It’s sense of smell has grown so that it can smell the hole the seal frequents and it can then smell when the seal emerges, this has been developed over many years of hunting. The seal leaves behind a distinct smell when it surfaces from the breathing hole, from that scent the polar bear is able to tell if the hole is visited frequently or if it is an older hole and not worth waiting.

The polar bears adapted sense of smell also helps them sniff out carcasses of animals that have starved or been half eaten. This is incredibly important for teenage bears as they often have to scavenge because they are not yet strong enough to defend their kill or sometimes their parents die and they cannot yet make a kill by themselves.

2: One of the main structural adaptations of the polar bear is its enormous size. As the largest terrestrial carnivore and largest bear, a male adult weighs in at 350- 680 kilograms, with females being about half the males size. Females can weigh up to 500 kg during pregnancy however. The largest polar bear recorded was a male who weighed in at 1002 kilograms. It’s enormous size means that it has no real predators. It is too big and too strong for any animal to really bother it.This helps it survive by making it almost impossible for anything to actively prey on the polar bear.

Perhaps more importantly, its tremendous size means it is able to retain heat better, which is crucial in the environment it lives in. The bear has been forced to evolve to meet its habitat cruel demands, one of these is to be able to deal with extreme environmental pressures like severely cold temperatures and lack of food during summer. The polar bear is able to store fat and fast for months without eating. It has adapted well in the arctic environment.

3: Another structural adaptation of the bear is its fur. They actually have two layers of fur. The first or outer layer, the “guard fur” is up to 15cm long and protects the denser underfur. This provides excellent insulation for the bear throughout the year. The bear molts from May to August, it does this gradually however so that it has sufficient insulation year round.

This adaptation can be linked to the second adaptation in the way that they are both caused by the extreme cold of the habitat in which the polar bear lives. The size of the polar bear alone is not enough to keep it warm, it must be coupled with its double layered fur, just like the fur alone is not enough to provide sufficient warmth for the bear.

4: The polar bear has developed soft papillae( small bumps ) on its feet that provide better traction on the ice. This may seem like a small adaptation but in fact almost all adaptations are major and contribute to the animal coping better in its environment. The extra traction is absolutely essential for the bear as it spends most of its life on the open ice hunting for seals or other types of food. Without these small bumps on their feet the bears would not be able to hunt successfully and would have died off over the harsh winters.

5. The polar bear originally evolved from the brown bear, the brown bear was a big bear that had fairly long legs compared to the polar bear. The polar bear has changed dramatically from the brown bear. It now has short, stocky legs that also help it to conserve heat by reducing the bears surface area.

These legs also provide a strong base for the polar bear, they create incredible power as shown by polar bears being able to haul seals out of their breathing holes. If the bears didn’t have this strong base they would slip easily on the ice and not be able to hunt successfully.


 * <span style="font-family: 'Lucida Console',Monaco,monospace;">[[image:polar_bear_nose.jpg]] || <span style="font-family: 'Lucida Console',Monaco,monospace;">[[image:724polar_bear.jpg width="203" height="153"]] || <span style="font-family: 'Lucida Console',Monaco,monospace;">[[image:Polar_Bear_resting_gravel.jpg width="212" height="175"]] || <span style="font-family: 'Lucida Console',Monaco,monospace;">[[image:PANDA_PAW_1.jpg width="141" height="158"]] |||| <span style="font-family: 'Lucida Console',Monaco,monospace;">[[image:blue-polar-bear-wallpaper.jpg width="257" height="206"]] ||
 * <span style="font-family: 'Lucida Console',Monaco,monospace;">The Polar Bear’s adapted sense of smell. || <span style="font-family: 'Lucida Console',Monaco,monospace;">The Polar Bear’s enormous size. || <span style="font-family: 'Lucida Console',Monaco,monospace;">The Polar Bear’s insulating fur. || <span style="font-family: 'Lucida Console',Monaco,monospace;">The Polar Bear’s papillae provide traction. || <span style="font-family: 'Lucida Console',Monaco,monospace;">The Polar Bear’s hind legs are packed full of muscle. ||  ||

<span style="font-family: 'Lucida Console',Monaco,monospace;">// The Etruscan Bear (Ursus etruscus) // []

<span style="font-family: 'Lucida Console',Monaco,monospace;">The polar bear evolved from the brown bear and the brown bear is thought to have evolved from Ursus etruscus//.// This bear was similar in size to the brown bear and lived in many different environment. This bear is believed to have come from Ursus Minimus ( []) <span style="display: block; font-family: 'Lucida Console',Monaco,monospace; text-align: center;">This bear was similar in size to the brown bear and lived in many different environments.

<span style="font-family: 'Lucida Console',Monaco,monospace;">__Habitat__: Fossils of the Etruscan bear have been discovered in Greece, Tajikistan, Morocco, France, Georgia, Spain and Croatia. As many of these different places have different climates the bear must have been well adapted all round. <span style="font-family: 'Lucida Console',Monaco,monospace;">The climate in Greece is obviously drastically different from the climate in Croatia or France. It is likely that these fossils were of the same bear, but the bear had different adaptations to deal with the different habitats it lived in, not unlike the finches Darwin studied in the Galapagos islands.

<span style="font-family: 'Lucida Console',Monaco,monospace;">Greece’s climate is hot during the summer and remains relatively warm during the winter. It makes sense then that the bear that lived in Greece most likely would have had less fur or shorter fur, it would have been smaller and its weight distributed over its body more evenly than the polar bear and it also would have behaved differently to the bears that lived in colder climates. It most likely would have been more active than these bears.

<span style="font-family: 'Lucida Console',Monaco,monospace;">The bear that inhabited France would have been a balance between the two extremes, it would most likely have molted during the hotter seasons and possibly hibernated in the winter. France’s climate varies from cold to slightly warmer during the winter and summer. Therefore the bear would still be better suited to the cold than the bear that inhabited Greece would have been. <span style="font-family: 'Lucida Console',Monaco,monospace;">Bears that inhabited the colder climates like Croatia would have looked and behaved more like the modern day brown bears. It is possible that the brown bear( [] )<span style="font-family: 'Lucida Console',Monaco,monospace;">is the Etruscan bear that lived in these colder habitats.

<span style="font-family: 'Lucida Console',Monaco,monospace;">Adaptation 1: The Greek subspecies of the Etruscan bear most likely would have had shorter or less dense fur. This would have helped it survive by helping the bear release heat easier. Without being able to release the heat the bear would have overheated too much and died out quicker.

<span style="font-family: 'Lucida Console',Monaco,monospace;">The environmental pressure that caused this was the Mediterranean climate of Greece. It is hot all year round only cooling slightly during the winter.

<span style="font-family: 'Lucida Console',Monaco,monospace;">Adaptation 2: Again, the Greek subspecies of the Etruscan bear most likely would have had its body weight distributed more evenly across its body. This also helps the bear to survive by releasing heat quicker and it might also help it with the terrain in Greece. The bear might overheat and collapse from exhaustion without this adaptation.

<span style="font-family: 'Lucida Console',Monaco,monospace;">This adaptation would most likely have evolved because of Greece’s hot climate and also it’s terrain, the bear would have been able to expend more energy without overheating.

<span style="font-family: 'Lucida Console',Monaco,monospace;">Adaptation 3: The Greek subspecies of the Etruscan bear also would have had longer ears. This again helps to release heat quickly. In the severe heat of Greece being able to release heat quickly is one of the main factors that help animals to survive. Without being able to release heat the bear might suffer from heat stroke.

<span style="font-family: 'Lucida Console',Monaco,monospace;"> This adaptation was also caused by the same environmental pressure that caused the first two adaptations, heat.

<span style="font-family: 'Lucida Console',Monaco,monospace;">Adaptation 4: This bear also would have had a keen sense of smell, a trait it appears it passed onto modern day bears. This would have helped it hunt better, it would have been able to track animals trails easier, leading it to its meal. Without its sense of smell the bear might not have been able to hunt successfully and could have starved.

<span style="font-family: 'Lucida Console',Monaco,monospace;">The environmental pressure that caused this would have been that the animals in Greece would have been quicker than the bear usually and it would have had to be able to follow them and ambush them.

<span style="font-family: 'Lucida Console',Monaco,monospace;">Adaptation 5: The subspecies of the Etruscan bear that inhabited Greece would have been smaller in size to the other subspecies of the bear. This would have helped it to hunt as well as lose heat. This helped it survive by making it more agile and quicker. It also helped it survive by absorbing less heat which means it can hunt more.

<span style="font-family: 'Lucida Console',Monaco,monospace;">The environmental pressure that caused this adaptation was the agility of the animals that the bear would have been forced to hunt in Greece as well as the harsh heat of that region.

<span style="font-family: 'Lucida Console',Monaco,monospace;">__Selection pressure__: Although the Etruscan bear of that time is no longer around, it never really became extinct. It just changed dramatically, the different subspecies of //Ursus etruscus// evolved into different modern day bears. The main bear descended from the Etruscan line being the brown bear. The Kodiak bear and polar bear are both descended from the brown bear, and if we follow the line even further back, the Etruscan bear.

**The Alaskan Polar Bear**
<span style="font-family: 'Lucida Console',Monaco,monospace;">It is 50 years in the future, making the year 2061. The polar bear has been forced to evolve. The climate is warmer and the arctic is completely melted, the polar bear has been forced to migrate to Alaska. The polar bear has been forced to evolve in drastic ways to meet the needs of its new climate. There is now vegetation growing in the bear’s habitat, the oceans are also warmer and there is more than just seals on the menu now. The ground is covered in snow nearly all year round.

<span style="font-family: 'Lucida Console',Monaco,monospace;">There is now more vegetation that the polar bear has adapted to. There is small ferns that grown in the snow and there are large cluster of Alaskan pine trees that are 6-18m high and 0.1m to 0.3m in diameter. The vegetation is well adapted to the cold, losing its leaves during the winter and growing them back at the start of spring.

<span style="font-family: 'Lucida Console',Monaco,monospace;">The animals that live in Alaska are still big enough to provide the polar bear with enough sustenance to keep it alive through the still cold winters. Animals like rein deer and moose are the polar bears main diet in this new environment, although it occasionally is able to catch some smaller animals. There is an abundance of life in this new habitat compared to the arctic that it used to live in.

<span style="font-family: 'Lucida Console',Monaco,monospace;">The polar bear usually ambushes its prey in the clusters of pine trees by sneaking up through the dense cover of snow. The animal is not able to hear the bear sneaking up on them because of the constant wind in this environment. Although it is not quite as harsh as the arctic, the polar bear still needs special adaptations to survive. <span style="font-family: 'Lucida Console',Monaco,monospace;">Adaptation 1: The polar bear that now lives in the Alaskan wilderness no longer retains as much fat. The bear is forced to hunt quicker animals that it can’t ambush as easily as the seals, it must be able to run to catch its food. If it did retain fat it would not be able to catch its prey and it would overheat quicker, leading to eventual starvation.

<span style="font-family: 'Lucida Console',Monaco,monospace;">The environmental pressure that caused this adaptation is the quickness of its new prey, the polar bear had the head start on seals as it was above them but not it is an even playing field and the bear cannot afford to be unnecessarily slow.

<span style="font-family: 'Lucida Console',Monaco,monospace;">Adaptation 2: The Alaskan Polar bear has developed stronger hind legs. This acts as propulsion for the bear as the kill is usually made within the first 50 meter chase. Without this propulsion the bear would not be able to accelerate quick enough and would quickly fall behind its prey, leading to starvation.

<span style="font-family: 'Lucida Console',Monaco,monospace;">This was caused by the same environmental pressure as the first adaptation. Quicker prey means the predator must become quicker or it will not be able to catch its food and it will not survive.

<span style="font-family: 'Lucida Console',Monaco,monospace;">Adaptation 3: The abundance of food in this region means that the Alaskan polar bear can afford to live in small groups.Some of this food is the Bison ( []), the Caribou ( []) and the Elk ( [] )<span style="font-family: 'Lucida Console',Monaco,monospace;">This has many advantages but the main two are that they can hunt easier as they can cut off the path of their prey. The second advantage is that there is more protection for the polar bears cubs from small predators that sometimes prey on them. This adaptation helps the bear to survive by providing more food and protecting the next generation of bears.

<span style="font-family: 'Lucida Console',Monaco,monospace;">This adaptation was caused by the abundance of food in the new environment as well as the new threat to the bears young. <span style="font-family: 'Lucida Console',Monaco,monospace;">Adaptation 4: The bear’s sense of hearing has become much keener, this helps it ambush prey as they cannot rely on eyesight because of the strong winds that are constantly blowing snow. This helps the bear survive by helping it locate food easier, without this the bear might not be able to hunt efficiently and could starve.

<span style="font-family: 'Lucida Console',Monaco,monospace;">This adaptation was caused by the strong winds that create poor visibility in this climate, especially during blizzards. <span style="font-family: 'Lucida Console',Monaco,monospace;">Adaptation 5: The bear now hibernates during winter when food is short. This helps the bear to survive by conserving energy when there is no source to create more energy as the other animals have migrated for the winter. If the bear didn’t hibernate it would expend too much energy and eventually starve.

<span style="font-family: 'Lucida Console',Monaco,monospace;">The environmental pressure that caused this was that the other animals are less adapted to the cold than the bear, they must migrate to warmer areas in the coldest parts of the winter to survive and the bear cannot afford to follow them.



<span style="font-family: 'Lucida Console',Monaco,monospace;">The selection pressure that caused the polar bear to migrate and evolve into the Alaskan Polar bear was the warming of the planet, more specifically, the melting of the arctic. As there is no solid land mass under the arctic the polar bear was forced to migrate to Alaska. They were then forced to change to their new surroundings and branched off from what the polar bear was originally like. The polar bear did not truly become extinct but like its ancestor the Etruscan bear changed over the years into a different species.

**__Bibliography :__** Polar Bear, (2011), Retrieved June 1, 2011, from [] The Polar Bear Habitat, (2011), Retrieved June 1, from [] The bear and cavebear in fact, myth and legend, (2011), Retrieved June 2, from [] Trees of Alaska, (2011), Retrieved June 2, from [] Arctic, (2011), Retrieved June 2, from [] Ursus Etruscus, (2011), Retrieved June 3, from [] Climate Of Alaska, (2011), Retrieved June 3, from [] Brown Bear, (2011), Retrieved June 4, from [] Climate of Greece, (2011), Retrieved June 5, from []