Because they are the essential micronutrients for the different metabolites of living organisms?
The complete statement is this: CNIDARIA exhibit two radial body forms, the polyp and the medusa, and use stinging cells to capture prey.
Cnidaria is categorized under the Animalia kingdom. It is made up of more that eleven thousand species, which all live in aquatic habitats; either fresh or salt water environments. There are four basic classes of cnidarians, these are: Anthozoa, Cubozoa, Scyphozoan and Hydrozoa. Their common feature is the cnidocytes, which are specialized cells that they use to capture their preys.
Cnidaria have two radial body types, which are called polyp and medusa. They used cnidocytes (stinging cells) to capture the foods they feed on.
Nature does = environmental stress or changes
