Why do echinoderms exhibit bilateral symmetry in their larval stage but radial symmetry as adults?
Larval Stage: Bilateral symmetry enables free-swimming larvae to balance and move efficiently in open water. Adult Stage: Adult echinoderms live on the seafloor (benthic zone). Pentaradial symmetry allows them to feed and detect surroundings equally from all directions.
Ref: NCERT Biology Textbook - Latest Edition for Academic Session 2026-27 (Zoology section, Rationalized Textbook for Class XI and XII), Chapter: Biology - Zoology portion (Latest NCERT Textbooks for Academic Session 2026-27 - Rationalized Edition for Class XI and XII), Topic: Structural organization, physiology, human health and related concepts as per latest syllabus.