1. Phylum Cnidaria Jellyfish, hydra, sea anemones, & coral

2. Appearance Polyp: cylindrical, pine shaped animals that are usually attached to a rock or Ex. Hydras, sea anemones, corals Medusa: bell-shaped body; umbrella Ex. Jellyfish *Have 2 tissue layers: ectoderm & endoderm

3. Appearance (cont.)

4. Appearance of a jellyfish

5. Symmetry Radial symmetry

6. Skeletal/Muscle System most have primitive muscle cells; coral have external skeleton of calcium carbonate

7. Capturing Prey LET’S EAT!!! cnidarians are carnivores (eat meat) that use tentacles arranged in a ring around their mouth to capture prey when a “trigger” is stimulated on a stinging cell called the cnidocyte, a harpoon or nematocyst shoots out & injects poison into the prey

8. Capturing Prey: Cnidocyte and Nematocyst at work: Cnidocyte (stinging cell) Nematocyst (harpoon )

9. Digestion Sac w/ a digestive cavity (gastrovascular cavity) w/ a single opening that acts as a mouth/anus Jellyfish Hydra

10. Digestion (cont.) food is pushed into the gastrovascular cavity where digestion begins (extracellular digestion) then food is passed to food vacuoles of gastrodermis undigested remains leave through the mouth/anus

11. Nervous System Nerve Net- Cnidarians do not have a brain but they have simple sensory receptors that detect & respond to stimuli

12. Circulation NONE!!

13. Respiration Diffusion- oxygen from water moves into gastrodermal cells (high to low)

14. Reproduction Asexual – budding- formation of outgrowths that pinch off from parent to live independently Sexual- forms a zygote and free swimming planula that settles on ocean floor; usually have separate sexes (male & female species) but some hermaphrodites do exist *MOST ALTERNATE B/W POLYP & MEDUSA LIFE FORM

15. Reproduction (cont.)

17. Excretion mouth/anus- release waste