The essential role of the algae is to carry out photosynthesis, while that of the fungus is less obvious, but it could be linked to the transfer of minerals within the thallus, to a repellent effect on herbivores and, above all, to resistance to desiccation of this living organism in the intertidal zone.
Although compared to lichens by certain authors,[2] mycophycobioses carry out an association of the opposite type: the algal partner is multicellular and forms the external structure of the symbiotic organization.
[3] To explain the nuances of this duality, the ecologists Chantal Delzenne-Van Haluwyn and Michel Lerond propose the analogy of the two symbionts with an "ideal couple".
[3] The term mycophycobiosis was introduced by Jan and Erika Kohlmeyer in 1972, based on the case of the brown algal species Ascophyllum nodosum, which regularly harbours the ascomycete Mycosphaerella ascophylli.
[6] While the only alga of the genus Prasiola remains subservient to a certain at least temporary marine cover, the mycophycobiotic association allows a more terrestrial conquest outside the intertidal zone.