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.
There are approximately 1,500 species of starfish found throughout the world, all of which are abundant at most ocean depths. All starfish species use a mouth located on the underside of their body to feed on ocean-bottom debris, as well as on mussels and clams. Occasionally, when the starfish encounters larger prey, it will force its stomach out through its mouth and digest the prey outside of its body.