Shaped by evolution, it describes all long or short-term exchanges and cooperation between animals to survive. It turns the traditional host-parasite relationship in a beneficial alliance for both partners. To describe mutualism, this fascinating and well-documented episode travels from the cold ocean depths to the heat of summer corn fields where unexpected couples have formed: manta rays and remoras, sea cucumbers and shrimps or else butterflies and ants got married for better or for worst.
