The organisms belong to the Cnidaria, which is a phylum of Kingdom Animalia. The characteristic features of the phylum are as follows-
1. They are aquatic organisms dominating the marine water.
2. Majority of them are sessile and have the cnidocytes or the stinging cells for capturing prey and defense from predators.
3. They are polymorphic and have two basic body forms called the motile medusa and the sessile polyps.
4. They are diploblastic and filter food particles out of the water to obtain nutrients.
5. The life cycle involves the both the polyp and medusa stages called the alternation of asexual and sexual phases.
