A group of animals which all have stinging cells and are predators. These include jellyfish, sea anenomes, hydras and corals. Corals have the best fossil record in this group.

Classes:

Anthozoans- Anenomes and Corals

Scyphozoans- Jellyfish

Hydrozoans- Hydra

For more information:

http://www.ucmp.berkeley.edu/cnidaria/cnidaria.html

http://www.palaeos.com/Invertebrates/Cnidaria/Cnidaria.htm