In Greek, echinos means hedgehog (spiny mammal), and derma means skin. Thus, these are spiny skinned organisms. These are exclusively free-living marine animals. They are triploblastic and have a coelomic cavity.
They also have a peculiar water-driven tube system that they use for moving around. They have hard calcium carbonate structures that
they use as a skeleton. Examples are sea-stars and sea urchins

Leave a Comment

Your email address will not be published. Required fields are marked *