Species Relationships
Landscape, climate and species interact with one another to form an ecosystem. There are, however, special links within ecosystems that help make up the larger picture of inter-species relationships. These relationships can be beneficial for both species involved, but relationships can also develop that are detrimental, sometimes even resulting in death.
Symbiosis is the most mutually beneficial type of relationship. It involves two species living together in some form to their mutual benefit. This is good news for both species involved, as they can both gain protection, opportunity for food, the riddance of "pests", or even a place to live. A good example of a symbiotic relationship is found in lichens. Lichens grow in diverse forms and colours, and live in even more diverse places such as trees, stumps and rocks. Although lichens look to be a single species of vegetation, they are actually comprised of two species: fungus and algae. The alga relies on the fungus as a body for structure and protection. The fungus absorbs the by-products created when the alga produces nutrients.
Commensalism is more of a one-sided relationship. A commensalistic relationship is one that benefits one of the species involved, but not the other. The other species is not usually negatively affected, and generally remains indifferent. However, in some cases it might lose out. An example of commensalism can be found on many species of trees - perhaps even in your own backyard! Many epiphytic plants grow on the sides of trees and use them as a support without stealing any of the tree's nutrients.
Parasitism is a type of predation that maximizes the use of resources. It is true that all animals are in essence a type of parasite, as they need to kill other species (plant or animal) in order to live. Parasitism, however, is different in that the parasite lives within or on the larger animal, negatively affecting its daily life. There are, however, some parasites that take what they need without negatively affecting the host. An example of a parasite is the common leech, that sucks the blood of many large mammals.