The phylum Cnidaria contains what kind of organisms

They are mostly made up of water animals.

Explanation:

The phylum cnidaria also known to be coelenterates are aquatic animals that include hydra, sea anemone, jelly fish and coral polyps. They have cells and tissues, with bodies that are radially symmetrical.

Cnidarias reproduce asexually by producing outgrowths from their body walls known as buds. Budding often occurs during the favourable season when food is bountiful.

They also reproduce sexually by producing male and female gametes. In the hydra, both testis and ovary is found in the same individual; though jelly fishes have separate male and female individuals.