Which organisms are examples of Echinodermata?

• A. Starfish
• B. Jellyfish
• C. Sponges
• D. Corals

Answer: (A)

Echinoderms are marine animals defined by features like pentaradial symmetry as adults, a water vascular system with tube feet, and an internal calcium-containing skeleton. Starfish show all of these clearly: their bodies are organized around five or more arms radiating from a central disk, they use a network of water-filled canals with tube feet to move and to feed, and they have a calcified endoskeleton. Jellyfish lack these traits and are cnidarians, not echinoderms. Sponges have no true tissues or organs, so they don’t fit either. Corals are also cnidarians that build calcium structures but don’t have a water vascular system or endoskeleton like echinoderms. So the organism that exemplifies Echinodermata is the starfish.