Abstract:
A diverse and ecologically important range of nonparasitic plants and animals inhabits the surfaces of other organisms, and, in the case of epifauna, also occurs on nonliving aquatic surfaces. Some epibiota have an intimate relationship with their host, but for many the host is just a surface to which they can attach, shelter from consumers, or gain better access to resources. Epibiota tend to be most abundant on large, long-lived, and structurally complex surfaces. In forest canopies, epiflora are often unproductive due to water and nutrient limitation, but nonetheless increase animal diversity by providing habitat, food, and water. In aquatic ecosystems, epiflora and small mobile epifauna are highly productive and support abundant consumer populations, while filter-feeding epifauna link pelagic and benthic ecosystems by accelerating the flow of organic matter from the water column to the seafloor. Epibiota on living surfaces interact with their host in a number of ways, with varying net effects on each partner. Sessile epibiota reduce their host’s access to light and nutrients, and increase the likelihood of host tissue damage, but mobile epifauna often benefit their hosts by keeping them free of epiflora or protecting them from predators.