Solution

The Cnidaria is a group of animals including corals, sea anemones, sea pens, sea pansies, jellyfishes, and hydroids, are among the most beautiful of all marine invertebrates. The vast majority occur in salt water, but there are a handful of freshwater species. Fewer than 1% of cnidarian species occur in freshwater. In freshwater, the Cnidaria is represented by the class Hydrozoa.