Introduction to Sea Stars: Sea Stars have systems that are very simple but incomparable to other organisms. Even though Sea Stars seem very basic with their star appearance and striking colors, the roles of all of its organs and body systems perform tasks other may not be able to. Sea Stars are invertebrates and organisms with no head, but tube feet and arms where they can sense as well as see. These five arms or more, can regenerate them as long as the central disk is not affected. They have radial symmetry and an oral surface as well as aboral with the arms and disk covered with spikes. As you read you will come across many differences in the Sea Star as an organism for example the fact that they have no blood, no brain, or a stomach outside their body, but when you take a closer look into their systems similarities appear when compared to humans.