The spines of Diadema antillarum are brittle and will fragmentize if wounded. The pieces are difficult to remove, and often cause infections as they carry bacteria. The mucous coating of the spines, normally used to kill organisms that live in the spines, carries a mild poison that also aids in deterring smaller predators. Diadema antillarum has been observed to gather in groups as an added protection.
- Carson, R. 1955. The Edge of the Sea. Boston: Houghton Mifflin Company.