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.
The larvae settle to the sea floor and adopt their distinctive adult radial symmetry. Sea Stars. Sea stars, also known as âstarfishâ, are probably the most well known echinoderm of the sea. The common name âstarfishâ is quickly being replaced by the more accurate term âsea starâ.Since starfish have no relation to fish, the term âsea starâ is preferable.he most striking feature of all echinoderms is their pentamerous radial symmetry. That is, the body can be divided into five parts (or appendages) which point outward from the center of the body. Interestingly, although most mature echinoderms are radially symmetrical, the larvae usually have bilateral symmetry.