1. Polar Bears
Naomi Rodriguez

2. Background
Polar bears have lived in the arctic for many years.  Their bodies have adapted and developed in order for their survival in the polar region. 
Polar bears are able to live in the deep freeze for many reasons. 
They have thick fur that keeps in their body heat. 
They have small ears and a small tail which means they loose less heat. 
Their paws are so big that they act like snowshoes, and the pads on their feet have an anti-slip skin, which would be similar to sandpaper. 

3. Types of ecosystems Polar bears ecosystem is the Arctic ecosystem,
Complex food web that is formed by its distinctive plankton, animal species, and environmental factors.

4. Population size
 there are 20,000 to 25,000 polar bears in the world.

5. Historical references
The National Museum of Natural History receives numerous requests from the general public, universities, public and private institutions, and professionals for information on Polar Bears, Marine and Sea Otters. This bibliography is meant to serve as an introductory guide to that subject listing publications which for the most part are in print or available from technical information services. Popular references include magazine articles and several references appropriate to young school children. Additional technical references may be located in technical journals and indices such as the Journal of Mamma logy, Wildlife Review, Zoological Record, Biological Abstracts and the Canadian Journal of Zoology.

6. Facts
The polar bear is one of eight species of bears that exist on the planet today.
Polar bear evolved from eastern Russian or Alaskan grizzly bears some 200,000 to 500,000 years ago.
The height of polar bears at their shoulders when they are on all fours is usually between 3.5 to 5feet (1 to 1.5 meters) for males and females

7. What happen?
Often referred to as the largest land carnivores in the world, polar bears are actually marine mammals, and spend much of their time on Arctic sea often ice hundreds of miles from land. Climate change is melting their icy habitat, making it increasingly difficult to travel, hunt and raise their young. The sea ice they depend on melts earlier each spring and forms later each fall.

8. Causes
Effect on polar bears. Polar bears rely on the sea ice to hunt, breed, and, in some cases, den. Changes in their distribution or numbers affect the entire arctic ecosystem.

9. Persons on fault
Polar bears and other Arctic species are particularly at risk because their habitat is increasingly threatened by the rising temperatures. Numerous scientific agencies have shown that polar bear numbers are on the decline, and that if action is not taken quickly, these animals may vanish from the Earth, deprived of habitat, food, and shelter.

10. Response
The polar bear uses the same systems as humans to detect stimuli, this being nerves, touch, sight, hearing, taste and smell. However, these systems are specially adapted for the polar bear's life style. The nerve system is the same as of that of humans.

11. Cleanup
Polar bear like to keep themselves clean because it helps the insulating properties of their fur. After feeding they’ll usually wash by taking a swim or rolling in the snow. They also roll in the snow to cool off.

12. Environmental Concepts
Chapter 11 Water Resources
It talks about surface water
This is relative with polar bears, because polar bears go into the water.

13. Damage Report: Population
There are 19 distinct subpopulations of polar bears living in the Arctic, and each population will be affected somewhat differently.

14. Ecosystems destroyed
Large carnivores are sensitive indicators of ecosystem health. Polar bears are studied to gain an understanding of what is happening throughout the Arctic. A polar bear at risk is often a sign of something wrong somewhere in the arctic marine ecosystem.

15. Short- term
Polar bears detected and actively responded to approaching snowmobiles was measured and the behavioral response was recorded.

16. Long- term
The polar bear is considered an indicator species of ecosystem health because of its longevity, life-history requirements, reliance on sea ice, and position in the Arctic food web.

17. Could this happen again?
There has been much worry about the possibility that global warming will cause the polar ice caps to melt and flood many coastal cities. Coastal flooding could be catastrophic because virtually all of the world's metropolitan areas that have more than 10 million people are located on or near coasts.

18. Similar risk as polar bear
Fish have the same risks.