Metagenesis is seen in:

Step-by-step solution

Cnidarians exhibit two basic body forms called polyp and medusa. The former is a sessile and cylindrical form like Hydra, Adamsia, etc. whereas, the latter is umbrella-shaped and free-swimming like Aurelia or jelly fish. Those cnidarians which exist in both forms exhibit alternation of generation (metagenesis), i.e., polyps produce medusae asexually and medusae form the polyps sexually (e.g., Obelia ).