NC State University
North Carolina State University: Symbiotic Relationships
Includes a description of symbiosis in general, then lists and defines types of symbiosis including mutualism, commensalism, parasitism, competition, and neutralism. Includes a chart which summarizes the different types of relationships....
PBS
Pbs Learning Media: Historic Relationships Between Dogs and Humans
In this video segment from Nature, learn the history of the world's first domesticated animal, the dog. [7:34]