Which characteristic is common to a starfish and snail?

Question

both are invertebrates

both are the same size

both are mollusks

both are echinoderms

Answer 1

Neither option 2 (both the same size) nor option 3 (both are mollusks) is correct. Option 1 (both are invertebrates) is partially correct, as both starfish and snails lack a backbone or vertebral column, making them invertebrates. However, the better answer is option 4: both are echinoderms. While snails are classified as mollusks, starfish belong to a separate phylum called Echinodermata, which includes other animals such as sea urchins and sand dollars. Echinoderms are known for their radial symmetry and unique water vascular system.