This first group of animals have no backbone. The Porifera, or pore-bearers, are the sponges. They are very primitive animals that are like thousands of Protists all working together as one. They are able to glue onto the bottom of the ocean or on a rock and absorb the water as it washed over them. The Cnidarians are stinging jelly-like animals.
Cnidarian comes from a Greek word meaning stinging nettles.
All Cnidarians have stinging cells called nematocysts. They sting their prey with the tentacles surrounding their mouth. Then it pulls its anesthetized prey into its mouth. For the first time, animals seem to have some kind of symmetry or mirror image of itself on its body. The Cnidaria's symmetry is called radial symmetry.