The crown of thorns starfish is a large, multiple-armed starfish (or seastar) that usually preys upon hard, or stony,coral . The crown of thorns receives its name from venomous thorn like spines that cover its upper surface, or the crown of thorns. It is one of the largest sea stars in the world.
The crown of thorns starfish is very common in the Indo-Pacific ocean. It occurs at tropical and subtropical latitudes from the Red Sea and the east African coast across the Indian Ocean, and across the Pacific Ocean to the west coast of Central America. It occurs where coral reefs or hard coral communities occur in this region.
The body form of the crown of thorns starfish is fundamentally the same as that of a typical starfish, with a central disk and radiating arms. Its special traits, however, include being disc-shaped, multiple-armed, flexible, prehensile, and heavily spines, and having a large ratio of stomach surface to body mass. Its prehensile ability arises from the two rows of numerous tube feet that extend to the tip of each arm. In being multiple-armed, it has lost the five-fold symmetry typical of starfish, although it begins with this symmetry in its life cycle.
Adult crown-of-thorns starfish normally range in size from 25 to 35 cm . They have up to 21 arms. Although the body of the crown of thorns has a stiff appearance, it is able to bend and twist to fit around the contours of the corals on which it feeds. The underside of each arm has a series of closely fitting plates which form a groove and extend in rows to the mouth. They are usually of subdued colours, pale brown to grey-green, but they may be garish with bright warning colours in some parts of their wide range.