2. Phylum Cnidaria

3. The Cnidarians 9000+ species Jellyfish Sea anemones Corals Hydra

4. Characteristics Entirely aquatic, mostly marine Radial symmetry, no definite head Nematocysts: stinging cells used for predation and protection

5. Two Body Forms Polyp Sessile, attached, cylindrical Medusa Bell or umbrella shaped, can swim with jet propulsion

6. More Characteristics Tissue level of organization No coelom Gastrovascular cavity with one opening for digestion and circulation Reproduction is both sexual and asexual Asexual: budding in polyps Sexual: gametes in all medusa and some polyps

7. Phylum Cnidaria

8. Class Hydrozoa “water serpent” Solitary or colonial Hydra: basal disc for attachment Obelia Portugese man-of-war

9. Class Scyphozoa “Cup Animal” Solitary Bell shaped medusa: bell may 2 meter diameter, tentacles up to 70 meters long jellyfish

10. Class Cubozoa Cube jellyfish Bell is square Used to be considered a sub- class of Scyphozoa

11. Class Anthozoa “Flower Animal” All polyps Flower like appearance Coral Sea anemones Sea fans

12. Sea Fan Sea Anemone

16. Coral Reefs Coral reefs are formations of calcium carbonate (limestone) Deposited over thousands of years Living plants and animals are on the top layer More is being constantly deposited