Acanthaster is a genus of starfish that includes A. planci, commonly known as The Crown of Thorns Starfish. This Starfish is of great concern because they can devastate reefs when found in plague proportions. They can grow up to 1m in width and eat their own body weight in coral every single night. Click on the link above to read more about the starfish itself. If you wish to learn more about the threats that the Starfish puts on The Great Barrier Reef, click here.