Question

During the metagenesis of Obelia,

• A. polyps produce medusae asexually and medusae form the polyps sexually.
• B. polyps produce medusae sexually and medusae form the polyps asexually.
• C. both polyps and medusae are produced sexually by each other.
• D. both polyps and medusae are produced asexually by each other.

Answer 1

Answer: (A)

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 jellyfish. 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).