How Polar Bears Survive Extreme Environments

Polar Extremes  
 

Introduction: The Polar Bear (Ursus Maritimus) or more commonly known as the Ice bear. The Polar bear lives in the Arctic, a polar region located at the most northern part of the Earth. The Arctic consists of the Arctic Ocean, Iceland, Northern Canada, Sweden and other countries. Land within the Arctic region has seasonally varying snow and ice cover, with predominantly treeless permafrost-containing tundra. The Arctic region is a very unique area among the many of Earth’s ecosystems.  (Wikipedia, Arctic, 2019)

 The Polar Bear is found in the Arctic Circle and in adjacent land masses as far south as Newfoundland. Due to the absence of human development in its isolated habitat, it retains more of its original range than any other extant carnivore. While they are rare north of 88 degrees there is evidence that they range all the way across the Arctic, and as far south as James Bay in Canada. Polar bears are marine mammals because they spend many months of the year at sea, usually (3-5) However, it is the only living marine mammal with extremely powerful, large limbs and feet that allow them to cover kilometers on foot and run very fast on land. Its preferred habitat is the annual sea ice covering the waters over the continental shelf and the inter-island Arctic archipelagos. These areas, known as the “Arctic ring of life”, have intensely high biological productivity compared to the deep waters of the high Arctic.  (Wikipedia, Polar Bear, 2019)

Figure 1: The Arctic (northern most part of the Earth), retrieved from https://en.wikipedia.org/wiki/Arctic 

Figure 2: Polar bear, retrieved fromhttps://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwisjqfD7LfiAhUNcCsKHaT6AFgQjRx6BAgBEAU&url=https%3A%2F%2Fabcnews.go.com%2FInternational%2Fcanadian-man-dies-protecting-children-polar-bear%2Fstory%3Fid%3D56417853&psig=AOvVaw2tn1OHOCuIqyg-AXs4UPZq&ust=1558913780708983

Structural Adaptation of a polar bear 

A behavioural adaptation polar bears have adapted to make structural over years is eating fat and not protein has another benefit, it means that the bear does not have to excrete large amounts of nitrogen from the protein which being a mammal would be in the form of urea in the urine. Excreting urea requires a small amount of water to be lost, while the bear could eat snow to replace this, it would use an extreme amount of energy to warm the bear back up again, eating fat simply solves the problem.  

Another structural adaptation is having thick fur on the large paws, the colour is icy white so that it helps them blend in with the ice and snow so that they can sneak up on prey and catch them off guard looking like moving ice. The thick fur provides insulation from the freezing snow and ice, so they don’t slip on slippery surfaces and get cold. The paws are also large to help spread the polar bears weight over ice and snow and have blubber under the pads for extra insulation, this evolved adaptation has allowed them to survive in the icy extreme environment, without the insulation and fur the polar bear would not have survived in the icy conditions. (Barrow, 2019)

Physiological Adaptation of a polar bear 

A physiological adaptation of Polar Bear’s is when females are pregnant, they go into hibernation in their den during the winter so that they can give birth. Males and females that aren’t pregnant don’t make dens and don’t hibernate. 

Their body temperatures do not drop substantially when hibernating, and other body functions also continue. When hibernating, a female’s body temperature may drop slightly, perhaps to 35° Celsius, or it might remain normal at 37° Celsius. The female polar bear’s heart rate decreases to around 27 bpm from a normal resting heart rate of around 46 beats per minute. Females fast (go days/months without eating) throughout hibernation. They may lose all or most their fat stores in doing this. Unlike a lot of other hibernators, female polar bears give birth while hibernating. Although hibernation females sleep soundly, they’re easily and quickly aroused. 

This is both a structural and physiological adaptation. Thick layer of body fat, this can be more than 10cm (4 inches) thick, it is used for both insulation and also food storage to help survive when food supply may be irregular; especially in the summer months when bears often go hungry for long periods due to not beings able to hunt their preferred food of seals. Up to around 50% of a polar bears weight can be fat. It also really helps them to float naturally when swimming so avoiding having to use energy to keep their head out of the water which would make them freezing cold due to the icy temperatures of the Arctic. (Ward, 2019)

Figure 3: Hibernating polar bear, retrieved from https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwj_iM2c7bfiAhXg6nMBHQBsAq4QjRx6BAgBEAU&url=https%3A%2F%2Fpolarbearfacts.net%2Fdo-polar-bears-hibernate%2F&psig=AOvVaw245tT9GCxZaQOj_3y24JYL&ust=1558913955033028

Behavioural Adaptations of a polar bear 

Polar bears exhibit a bit of aggression to protect their cubs or food and to compete for females (mating). Their mode of communication is most commonly vocalization and sign language.  

The adaptation of using body fat during hibernation is used so that they can conserve all their energy through the deep sleep (since they are fasting). Polar bears can also use it during conditions of food scarcity (and not just during hibernation). They need this in their environment because pregnant polar bears fast through hibernation and also because food can be scarce in their environment in the baron icy desert. 

Pregnant polar bears hibernate through the winter in their dens and their cubs are born in den, protected from dangerous weather outside, meaning they are healthier and have better survival chances 

Polar bears also have nostrils in which they can open or close on command, this is used for them because they swim under water and it’s become a regular task for polar bears to do whilst hunting and migrating. They close their nostrils so salt water doesn’t get into it their nose when swimming. (international, 2019)

Figure 4: Polar bear swimming, retrieved from https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwjwtqjV7bfiAhUYiHAKHZntDUcQjRx6BAgBEAU&url=https%3A%2F%2Fpolarbearfacts.net%2Fhow-fast-can-polar-bear-swim%2F&psig=AOvVaw2ZqECklFt4Y5SSn1Tuj4SV&ust=1558914079713811

Environmental challenges for polar bears in the Arctic the lack of food in the baron wasteland desert. Usually polar bear’s hunt seals as their main source of food, but they also hunt Beluga whales, other Polar bears, Walruses, Narwhals and Arctic fox. Since it is sometimes hard to catch a seal out of water the Polar bear fasts for up to 12 months in summer, in winter it is most commonly around 4 months. Another challenge for Polar bears in the Arctic is global warming; this is a huge problem considering the Arctic is made of ice and snow. With global warming comes heat melting the ice so that rocks will be the most of what’s left of the Arctic in the next few years unless we humans do something about it, thousands of polar bears will die if we don’t. Environmental challenge number 3 for polar bears is oil exploration. As the apex predator of the Arctic, polar bears don’t have to deal with being hunted but they do have to deal with human’s mistakes and oil spillages. A polar bear’s fur keeps them insulated in the icy cold desert of the Arctic, if oil gets on these precious animals fur it can reduce the effect of the insulation which means the bear will have to use more energy and increase its meal intake which can be very difficult. Polar bears can also eat contaminated prey such as seals that have been swimming in oil, which could cause liver and kidney damage as well as long term toxicity. If oil spills and mistakes keep happening the Arctic will no longer be a safe place for these animals to continue living in. (Wildlife, 2019)

Figure 5: Oil drilling in the arctic. retrieved from https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwikpImq8rfiAhVRXn0KHfZ2DhYQjRx6BAgBEAU&url=https%3A%2F%2Fwww.nytimes.com%2F2018%2F12%2F03%2Fus%2Falaska-oil-drilling-polar-bears.html&psig=AOvVaw2RmyDdBN

Conclusion: The key adaptations of a polar bear are its White Fur, the ability to fast and its large paws. These all work together to produce the apex predator of the Arctic, its white fur to blend in with the snow and help it camouflage into the background, the ability for the bears to fast months on end without eating and its large paws help spread the polar bears weight across the ice as well as helping the polar bear not slip on the icy surface. When a polar bear wants to catch a seal it can camouflage into the background and slowly move towards it, for the polar bear to successfully make a catch he must be quick and agile, the large paws help the bear swiftly run across the ice to catch the seal. If the polar bear doesn’t catch the seal he may have to wait for months to catch another one, but he will keep persisting till he can find his next meal, the ability to fast is a very important feature because if polar bears couldn’t fast there would be none left as the Arctic is very baron with life. These adaptations work together to overcome environmental challenges by helping the polar bear survive in these extreme conditions of the Arctic; an example of this would be the way polar bears hunt and catch prey such as seals and if they don’t then they at least have the option to fast for months on end.

Bibliography

• Barrow, M. (2019, may 26). Animal Adaptations and Survival. Retrieved may 26, 2019, from Science: http://www.primaryhomeworkhelp.co.uk/adaptations/polarbears.htm
• international, p. b. (2019, may 26). Behaviour. Retrieved may 26, 2019, from Polar bears international: https://polarbearsinternational.org/polar-bears/behavior/
• Ward, P. (2019, may 26). Polar bears facts and adaptations. Retrieved may 26, 2016, from Cool Antarctica: https://www.coolantarctica.com/Antarctica%20fact%20file/wildlife/Arctic_animals/polar-bear.php
• Wikipedia. (2019, May 26). Arctic. Retrieved May 26, 2019, from Arctic: https://en.wikipedia.org/wiki/Arctic
• Wikipedia. (2019, May 26). Polar Bear. Retrieved may 26, 2019, from https://en.wikipedia.org/wiki/Polar_bear: https://en.wikipedia.org/wiki/Polar_bear
• Wildlife, D. o. (2019, may 26). Polar bear. Retrieved may 26, 2019, from Defenders of Wildlife: https://defenders.org/polar-bear/basic-facts