The Joys of Symbiosis

In nature, there are the "Jeff Bezoses" (the exploitative bosses), but there are also the critters who help others. Well, they help themselves in the process, so they are influenced by positive interactions. This means that either both organisms benefit, or just one. These interactions are the best - neither species is harmed and the animal kingdom can finally live in harmony. These engagements are either mutualism or commensalism and can affect the mix of species found in natural communities. 

Mutualism is the best interaction on the list; it means that both groups benefit from each other. Even in our own bodies, there are trillions of bacteria swimming around in our guts that help break down the juicy hamburger that we ate the night before. They stop us from getting super bloated and they get some much-needed nutrients. Bees land on flowers to drink sweet nectar but also inadvertently pollinate other blossoms in the process, benefiting themselves, but also keeping vital plants alive. Also, in the coral reefs, teeny algae live in coral, doing the process of photosynthesis (turning sunlight into sugar), keeping the coral alive (and giving it some pretty colors). But the algae also get a great place to live, so they benefit too! Some species (like the bees) evolved together, so removing one species from the other would result in the entire ecosystem going haywire, and Earth would turn into a mess, to say the least. However, some organisms can survive without each other - they are just worse off. 

Commensalism isn't as good as mutualism, but still, no one gets harmed. Commensalism is an interaction that benefits one species, but neither harms nor hurts the other one. This is super common in nature as well.