Mutualism

Mutualism is a relationship between two organisms in which both benefit. It is a type of symbiosis which improves the biological fitness of both parties. The two organisms usually come from widely different types, often from different phyla or even kingdoms. The term is not used for any cooperation between animals of the same species.
Edouard van Beneden (18091894) introduced the term into evolutionary biology and ecology in the 1870s.
Examples: