Crown-of-Thorns Starfish is widespread in the tropic coral reef of Indo-Pacific Ocean. It used to be very rare in the coral reef vicinity of Taiwan. In the last two years, they seem to extend in Dongji and Xiji islands of Penghu. This starfish live in coral reef from 1 to 20 meters, feed on living coral tissues. Sometimes, we can find them preying on small organisms on the hard corals. Some coral reef areas are damaged heavily by this species, especially in the Great Barrier Reef.