ecosystems
What are ecosystems? ... All parts of the planet, from the highest microbe drifting in the atmosphere, to cockroaches, to the most exotic species in the deepest ocean trenches are all parts of ecosystems. All of these species can be considered parts of other ecosystems climbing up and down the ladder of species of the entire planet - each defined to serve a purpose. Even though you may look at the whole picture as one entire ecosystem it is in reality comprised of countless separate entities which are in fact their own ecosystems. Ecosystems are not necessarily stable, nor are all of their component species necessarily native to the area.