In cnidarians, which term is associated with motile form and which with nonmotile form according to the material?

• A. Polyp; Sessile
• B. Medusa; Planula
• C. Polyp; Medusa
• D. Sessile; Polyp

Answer: (A)

In cnidarians, two main life-form categories are polyp and medusa. The term most often linked to movement in many sources is medusa, the free-swimming, umbrella-shaped form, while polyp is typically anchored to a surface and considered nonmotile. The material used for this question, however, maps motile to the term polyp and nonmotile to sessile, so the pairing Polyp; Sessile aligns with that source’s terminology. To connect with the broader biology, remember that medusa is the actively moving stage, polyp is usually stationary, and planula is a free-swimming larval stage before settling as a polyp.