In cnidarians, which form is listed as motile in the material?

In cnidarians, which form is listed as motile in the material?

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

Answer: (A)

In cnidarians, motility is associated with the free-swimming forms. There are two main life-stage types to keep straight: the polyp, which is typically anchored to a surface and considered sessile, and the medusa, which is umbrella-shaped and free-swimming. There’s also the planula larva, a ciliated, free-swimming stage that travels before settling down or developing into the next form. So, the motile forms are the planula and the medusa, while the polyp is usually sessile. If your material lists a form as motile, it’s referring to one of these free-swimming stages rather than the sessile polyp.

In cnidarians, motility is associated with the free-swimming forms. There are two main life-stage types to keep straight: the polyp, which is typically anchored to a surface and considered sessile, and the medusa, which is umbrella-shaped and free-swimming. There’s also the planula larva, a ciliated, free-swimming stage that travels before settling down or developing into the next form. So, the motile forms are the planula and the medusa, while the polyp is usually sessile. If your material lists a form as motile, it’s referring to one of these free-swimming stages rather than the sessile polyp.