Non-parasitic symbioses between echinoderms and bacteria

During the last several decades, symbiosis has been described as a pervasive and evolutionarily significant biological phenomenon that has played a fundamental role in the evolution of life on Earth (Margulis 1976, 1991, Margulis & Fester 1991). The term symbiosis was first defined by the German mycologist Anton De Bary (1879) as “the living together of differently named organisms”. Such a broad definition naturally encompasses a wide variety of neutral, beneficial or detrimental interactions between heterospe-cific individuals and may thus refer to plant pollinisation by insects as well as to plant-herbivore or to prey-predator relationships. By insisting on the duration and contact, several authors sharpened…