Epizoan ecology and interactions in the Devonian of Spain
Abstract Shells of the brachiopod Anathyris phalaena (Phillips) from the Raneces Group (Emsian) of NW Spain are frequently encrusted by epizoans including Aulopora, Hederella, Spirorbis and trepostome bryozoans. Aulopora is preferentially distributed on dorsal valves, and all of the epizoans occur in greater densities on the median parts of the brachiopod shells. The unusual growth pattern of Aulopora colonies implies synchronous growth of the coral and the host brachiopod. The epizoans are interpreted as symbionts of living brachiopods which were able to survive for a short time after death of their hosts. Competition for living space on the brachiopod shells is indicated by epizoan overgrowths and fouling. Anathyris was one of several spire-bearing brachiopods which supported a symbiotic fauna of epizoans during Devonian times. The frequency worldwide of brachiopod encrustation evidently declines markedly into the later part of the Palaeozoic.