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-Sea Stars Description Anatomy Most starfish or sea stars are pentamerous, having five arms that radiate from a central disk. The sea star is covered with tough skin and sharp, calcareous spines.natomy. Most starfish or sea stars are pentamerous, having five arms that radiate from a central disk. The sea star is covered with tough skin and sharp, calcareous spines.