How are flatworms different from coelenterates?

Flatworms (Platyhelminthes) and coelenterates (Cnidaria) differ in several key aspects. Flatworms are bilaterally symmetrical, have a flattened body structure, and lack a true body cavity (coelom), while coelenterates exhibit radial symmetry and possess a simple body plan with a central gastrovascular cavity. Additionally, flatworms have a more complex organ system, including a nervous system and excretory structures, whereas coelenterates are primarily characterized by their specialized stinging cells (cnidocytes) for capturing prey. These fundamental differences reflect their distinct evolutionary adaptations and ecological roles.