The potential role of competition for space in a community depends on the arrangement of interaction relationships. A survey (255 m²) of the interactions between corals (Scleractinia) on a Caribbean reef (depth 10-30 m) indicated the outcome of 17-35% of the aggressive and defensive interactions to be unpredictable. Experiments on the reef (depth 7-13 m) with pairs of interacting corals - Madracis mirabilis, Agaricia agaricites, Montastrea annularis), Eusmilia fastigiata -- showed that, there are at least two additional processes which can result in a reversal of dominance: interference by epifauna and sweeper tentacle development. Employing laboratory and field experiments to distinguish between the impact of extracoelenteric digestion, epifauna behaviour and sweeper tentacles, the authors show the three processes combined to explain the coral interaction process in toto.