Q.What is metagenesis? Name one coelenterate that shows it.

Step 1. Coelenterates can occur in two structurally different body forms, the sessile polyp and the free-swimming medusa.

Step 2. In some species, both forms occur within the same life cycle, one generation giving rise to the other in turn.

Step 3. This alternation of generations is specifically termed metagenesis, and Obelia is the standard textbook example showing it.

Recall the definition of metagenesis and the standard example that shows it.

• Confusing metagenesis with simple asexual budding — metagenesis specifically means the alternation between the polyp and medusa forms, not just any form of reproduction.
• Naming Hydra, which does not show a medusa stage in its typical life cycle, instead of Obelia.