"An interaction between two species in which both species benefit." - Dictionary of Biology, Oxford Univ. Press

Honey Bee Pollenating a Cactus	Scarlet Cleaner Shrimp waiting at its cleaning station for a grouper with parasites.	Bullhorn Acacia: Ants live in thorn growths, fed by tree which it protects.
	This crab (Lybia ssp) uses the anemones in its claws for food and defense, offering the same to them in return.