Particular attention needs to be paid toward coral aggression when considering new coral purchases as well as placement. When certain corals are placed in close proximity or as they increase in size naturally their aggressive nature manifests itself and can be problematic. Corals have specialized mechanisms developed for protection and competition which include sweeper tentacles, mesenterial filaments and terpenoid compounds.
This is the most common defense mechanism found in the hard corals but also occur in some soft corals. These tentacles are not the same as normal coral polyp often being many times longer and containing specialized stinging cells. The effect of an attack on competing corals is that they can burn it to the point of severely damaging or even killing it.
These filaments produced by certain corals in their stomach can attack others in a way similar to digestion. Corals of the genera Favia, Favites, Scolymia, Pavona and Cynarina all have this ability.
This is the method of battle employed by soft corals whereby releasing compounds into the water to impede the growth of neighboring corals. By taking over additional space and growing above other corals they may result in blocking out the light and thus killing underlying coral.