Inducible Agonistic Structures in the Tropical Corallimorpharian, Discosoma sanctithomae

The Corallimorpharia are a group of softbodied anthozoans closely related to the scleractinian corals. Although numerous reports have documented the agonistic behaviors of actiniarians and hard corals, only Chadwick (1987) has shown such behaviors in a corallimorph (Corynactis california). The following investigation confirms the use of inducible aggressive structures in space competition in the laboratory and in the field by Discosoma sanctithomae. This tropical corallimorph used both modified marginal tentacles and mesenterial filaments to damage adjacent scleractinians. All colonies of Agaricia agaricites transplanted near D. sanctithomae were damaged. Initially, D. sanctithomae adjacent to Meandrina meandrites were severely wounded. However, 67% recovered and retaliated within a one to six month period, causing damage to M. meandrina that persisted for at least twelve months.