2. Among the invertebrates, Echinoderms are unique in possessing A. B. a water-vascular system. segmented bodies C. open circulation. D. wings 3. Which of the following describe(s) echinoderms? A. B. C. D. Calcareous endoskeleton directly under the skin. Hexaradial symmetry Digestion occurs completely outside of the organism. Incomplete gut 4. Echinoderms have superficial radial symmetry. Why are they included in the Bilateria? A. They have true tissues B. They really have bilateral symmetry, if one looks closely, with the madreporite being off-center. C. They are the sister taxon to the Chordata, are Deuterostomes, which are clearly within Bilateria. D. B and C are correct E. A, B, and C are correct 5. Sea cucumbers belong to the B. Asteroidea C. Holothuroidea D. Ophiuroidea. A. Echinoidea shuiroidea