Hint: Echinoderms are the marine animals. Starfish, sea Urchins, sea cucumbers are few examples of echinoderms. They have spiny skin and their body is adapted for sea water. They are mostly found in the sea bed.
Echinoderms are exclusively marine species with over 6000 species present in the sea. Few important characteristic feature of echinoderms are-
-They have a star. shaped body with spiny skin.
-They show organ level of organisation.
-They are triploblastic and have a coelomic cavity.
-The exoskeleton is made up of calcium carbonate.
The echinoderms have a distinct ambulacral system which helps the organisms in feeding (capturing food). This system starts from the mouth and ends at each arm. They have rows of hollow tube feet which can be extended and withdrawn.
-Vascular system- The echinoderms have a water vascular system.
-Radial canal- The radial canals are present in pentaradial animals through which water moves in and out of the body.
-Radial symmetry- The echinoderms have radial symmetry when adults.
Hence, the correct answer is E. Radial symmetry, radial canal, vascular system, and ambulacral system are the unique characteristics of phylum Echinodermata.
Thus the correct answer is option ‘E’.
Note: Echinoderms are poisonous and have sharp spines on their body which causes injury. Echinoderms are used for food. They are believed to increase the oxygen content in the sea bed. They use spines, toxins and sticky feet as defence against predators. The presence of water filled tube feet makes them marine.