Crown-of-thorns starfish 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 spined, 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 (pentamerism) typical of starfish, although it begins its life cycle with
Reef starfish or three months of their placement, while the mussels expanded within six months to cover 20-30% of the low zone when "S. australis" was removed. Without their predation, the mussels overwhelmed the area, threatening biodiversity. The juveniles of the species are detritivores. Reef starfish Reef starfish (Stichaster australis) is a species of starfish found in the South Pacific Ocean around New Zealand. A keystone species, the carnivorous starfish plays an important part in reducing the expansion of mussels. "S. australis" is pink or purple in color, with 11 arms. Found throughout New Zealand, "S. australis" is a keystone species in