Sümbioos on erinevate, kuid teineteisega kohastunud liikide, sümbiontide, evolutsiooniliselt kujunenud püsiv kooselu, mis on neile liikidele vastastikku kasulik või tarvilik.
Actions on lower animals, plants and micro-organisms are not eligible, except for those which are reared or cultivated on land or in fresh water or such organisms which are suited for use as biological control agents in agriculture. Exception will be made in the specific case of defined gene-for-gene relationships between parasite or symbiont and host, and where both organisms are to be conserved.
