 This niche specialization between species also leads to stabilization of symbiotic relationships between sessile and motile organisms.The ectosymbiotes can increase the fitness of their host by assisting with metabolism, nitrogen fixation, or cleaning the host organism.The diversity of advantages has yet to be fully explored, but by virtue of persisting throughout all of recent evolution, they likely confer an adaptive advantage to many of the species that exist solely due to ectosymbiosis.