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How Rainforests Work (1:59)
Rainforests are important because of their biological diversity, oxygen production, and vital role in world ecology. Learn more about rainforests in this HowStuffWorks video.
Ocean Waves (2:35)
From the archives of Discovery: Watch as a rescue helicopter and a bird interact with earth's largest ecosystem, the ocean. Learn more about the ocean in this video.
Planet Earth: Mountains: On the Edge (2:59)
The largest glacier lies in the Karakoram Mountains in Pakistan.
Essential and Endangered: Fishing (1:09)
Fishing along the Hudson River was banned when it was discovered that polychlorinated biphenyls that contaminate the water were also in the fish.
Essential and Endangered: Estuaries (1:18)
The ecotone characterized by the meeting of a river and the ocean is called an estuary.
