Echinoderms display radial symmetry, having 5 similar body extensions from a central point. Sand dollars live from the... endoskeleton made of interlocking calcium carbonate plates and spines. echinoderms move slow and live on bottom, so it is very important to sense in all directions. Why is radial symmetry an advantage for these animals? Where do echinoderms live? Which echinoderm is globular in shape? How do echinoderms move? Answer to: What are the defining characteristics of echinoderms? Characteristic of all echinoderms is the presence of an internal skeleton covered with spines and skin. Answered by. Many, but not all, echinoderms have spiny skin. By signing up, you'll get thousands of step-by-step solutions to your homework questions. Answer to: Do echinoderms have exoskeletons or endoskeletons? In sea stars and brittle stars, the skeleton consists of multitudes of small calcareous plates called 'ossicles' that move with one another, forming flexible joints. Ask for details ; Follow Report by Tiegoval 03/23/2018 Log in to add a comment Answer. Answer to: Why are echinoderms classified as animals? . Radial symmetry means that the body is a hub, like a bicycle wheel, and tentacles are spokes coming out of it (think of a starfish). Thanks 5. Echinoderm, any of a variety of invertebrate marine animals belonging to the phylum Echinodermata, characterized by a hard, spiny covering or skin. sea urchin. FLYBOI16 +6. Quizlet flashcards, activities and games help you improve your grades. tube feet. Beginning with the dawn of the Cambrian Period (542 million to 488 million years ago), echinoderms have a rich fossil history and are well represented As larvae, echinoderms are bilaterally symmetrical. Do echinoderms have a brain, nervous system? Describe three characteristics that allow them to live on the bottom. An echinoderm is a sea animal that has a hard spiny shell, or exoskeleton. Echinoderms live on the ocean bottom. Start studying Evolution of Echinoderms. The s … even classes of echinoderms are brittle stars, basket stars, sea urchins, sand dollars, sea lilies, feather stars, and sea cucumbers. Echinoderms usually have five appendages (arms or rays), but there are some exceptions. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Answer to: How do echinoderms move? Echinoderm study guide by irutazihana includes 44 questions covering vocabulary, terms and more. Rate! Start studying Echinoderms. There are over 6,000 species. kaypeeoh72z and 6 more users found this answer helpful Some species live in brackish water but all echinoderms are found in marine waters 5.0 2 votes 2 votes Rate! Learn vocabulary, terms, and more with flashcards, games, and other study tools. By signing up, you'll get thousands of step-by-step solutions to your homework questions. The skeleton varies with the type of echinoderms. sea cucumber. Echinoderms have what kind of skeleton?