High Quality Content by WIKIPEDIA articles! The crown-of-thorns starfish (Acanthaster planci) is a large nocturnal sea star that preys upon coral polyps. The crown-of-thorns receives its name from venomous thorn-like spines that cover its body. It is endemic to tropical coral reefs in the Red Sea, the Indian Ocean, and the Pacific Ocean. As solitary animals, they feed alone and maintain constant distance between themselves and other members of their species.