Use of the sea urchin Diadema antillarum (Echinodermata, Echinoidea) as a shelter for non-cryptobenthic juvenile reef fishes

Marine species can act as biogenic sources of habitat structures, increasing the web of interactions between reef fishes and the benthic environment. Among these species, sea urchins seem to play an ecological role that goes beyond the dynamics of coral-algal interaction on reef ecosystems. In this paper, we describe the commensal behavior of juveniles of two non-cryptobenthic reef fishes (Haemulon parra and Abudefduf saxatilis) with the sea urchin Diadema antillarum on sandstone reefs in Northeastern Brazil. Behavioral observations in situ raise the assumption that D. antillarum may provide an alternative source of shelter and therefore influence microhabitat complexity, particularly, for juvenile reef fishes.