Endangered species are very important as healthy ecosystems depend on plant and animal species as their foundations. When a species becomes endangered, it is a sign that the ecosystem is slowly falling apart. Each species that is lost triggers the loss of other species within its ecosystem (their predators). Humans depend on healthy ecosystems to purify our environment (such as air). When a species becomes endangered it is most likely due to loss of habitat and or loss of genetic variation. A loss of habitat can happen naturally. Human activity can also contribute to a loss of habitat by developing housing, industry, and agriculture. These factors reduce the habitat of native organisms.