Answer:
A Starfish is Triploblastic meaning they consist of three germ layers. Hydra are diploblastic meaning they consist of only 2 germ layers.
Explanation: Hydra live in freshwater habitats, whereas Obelia is exclusively marine. Hydra does not have medusa form in their life cycle, whereas Obelia has both forms; polyp and medusa. starfish," are not fish.
