Starfish Starfish Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea. Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or "basket stars". About 1,500 species of starfish occur on the seabed in all the world's oceans, from the tropics to frigid polar waters. They are found from the intertidal zone down to abyssal depths, below the surface. Starfish are marine invertebrates. They typically have a central disc and five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth,
Crown-of-thorns starfish damage includes a major section of the disk together with arms, the number of arms regenerating on the disk may be less than the number lost. Another hypothesis is the "aggregation hypothesis", whereby large aggregations of "A. planci" appear as apparent outbreaks because they have consumed all the adjacent coral. This seems to imply that there is apparently a dense population outbreak when there has already been a more diffuse population outbreak that has been dense enough to comprehensively prey on large areas of hard coral. Female crown-of-thorns starfish are very fecund. Based on the eggs in ovaries, 200, 300