Symbiotic Relationships


Mutualism: +/+
Both populations benefit. The interaction is necessary for the survival and growth of each species. e.g. crab and sea anemone


Commensalism: +/o
One population benefits. The other is unaffected. e.g. shark and fish; whale and barnacles


Parasitism: +/-
One population benefits (parasite) while the other is harmed (host). The interaction is necessary for the survival of the parasite. e.g. human and parasites; dog and fleas