epifaunaPronunciation: /ˈɛpɪfɔːnə/Definition of epifauna noun [mass noun] Ecology animals living on the surface of the seabed or a riverbed, or attached to submerged objects or aquatic animals or plants. Compare with infauna.Derivatives epifaunal adjective epifauna in other Oxford dictionaries Definition of epifauna in the US English dictionary