Most of us have a mindset that creatures living in water are all fish or relative of fish. But this is actually not so. There are different varieties of creatures living deep down the water. Not all breathe, move or feed the same way. One interesting creature is the star fish which is not said to be a fish at all. They belong to a section of marine members called echinoderms. Apart from star fish, there are sea urchins, sea stars, sand dollars and many more that belong to echinoderms family. They have identical body structure with a common centre from which attachments (or arms) emerge outward from the centre of the body. Except for a few exceptions, all echinoderms have the above defined body structure.
Echinoderms live in the seas and cannot be found on land or fresh water. There is a rich and varied life at the very bottom of the sea. Here mostly algae supply provides shelter for these echinoderms. These creatures mostly feed upon decaying matter on the sea floor.