- They are diploblastic animals , in which, the body is made up of two layers of cells:
- Ectoderm – One layer makes up the cells outside the body
- Endoderm – the other forms the inner lining of the body.
- These are mostly aquatic or marine habitat animals.
- Body shows radial symmetry.
- They have cavities in their body. Body cavity (coelom) acts as gastrovascular cavity i.e. coelenteron.
- Respiratory, circulatory and excretory organs are absent .
- They have a tissue level of organisation.
- Sessile forms are called Polyps and free-living forms are called Medusa.
For example : Hydra, Sea anemone