Richard E. Strassberg earned his Ph.D. in East Asian Studies from Princeton University.
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, granular or spiny, and is covered with overlapping plates.bout 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, 6,000 m (20,000 ft) below the surface.
Starfish are classified in the Class Asteroidea. All asteroids have several arms arranged around a central disk. Asteroidea are known as the true stars.. These animals are in a separate class from the brittle stars and basket stars, which have a more defined separation between their arms and their central disk.