What symmetry do echinoderm larvae exhibit?

• A. Bilateral symmetry
• B. Fivefold radial symmetry
• C. Radial symmetry in larvae
• D. No symmetry

Answer: (A)

Echinoderm larvae start with a bilateral body plan, meaning they have a left-right axis like many other animals. This bilateral symmetry reflects their developmental origin as deuterostomes and is seen in larval forms such as the typical starfish or sea urchin larvae. As they metamorphose into adults, echinoderms reorganize into a fivefold (pentaradial) arrangement, but that radial symmetry is a feature of the adult, not the larval stage. So, the larval stage is best described as bilaterally symmetrical.