DK Science: Cnidarians
Copyright © 2007 Dorling Kindersley
Cnidarians are water animals that have a simple, usually symmetrical, body with a mouth opening. Stinging cells on tentacles around the mouth catch prey. Cnidarians are either bell-shaped and mobile, like the jellyfish, or tubes anchored to one spot, like coral and sea anemones.
All cnidarians have stinging cells. Many are able to reproduce asexually (without mating) and sexually. There are 9,000 species.
(corals, sea fans, sea pens, sea anemones)
Features: anchored polyp (tube-like) form, carnivorous (eat flesh), often in groups
Features: some free-living, others anchored, most in colonies (large groups), mostly carnivorous