Defense Corals exhibit aggresion because of limited space available to live and grow. They compete with other coral species for space, food, and sunlight. They have mechanisms present to defend their territory. There are fighting tentacles that are 5 times longer than common ones with more nematocysts on each one. They attack other coral colonies by releasing a mucus at night.
Several attacks cause the neighboring family to die.
Some corals secrete a poison into the water or secrete matter to make it impossible for larvas of different corals to settle in the same area. Fringing reefs live in shallow water and borders the coast. Barrier reefs are separated from land by a lagoon. They grow parallel to the coast and are vey large. Atoll reefs are annular reefs that develop at or near the surface of the sea.