1. Phylum: Cnidarians

2. What is a Cnidarian? A cnidarian is an invertebrate
It uses stinging cells to capture prey
Examples:
Jellyfish
Corals
Sea Anemones

3. Body Structure All cnidarians have the following characteristics:
Radial symmetry
A hollow central cavity
Tentacles with stinging cells
However, cnidarians can have one of 2 different body plans.
Polyp
Medusa

4. Body Plans Polyp Mouth opens at top Vase-shaped Attached to a surface
Examples: Hydra, Sea anemone, Coral
Medusa
Mouth opens down
Tentacles point down
Adapted for a swimming life
Examples: Jellyfish

5. Activity: Color Code a Cnidarian
Endoderm
Tentacle
Jelly-like layer
(Mesoglea)
Ectoderm
Tentacle

6. Obtaining Food Stinging cells inject venom which paralyzes the prey
THINK! – Why are clown fish resistant to the toxins given off by sea anemones?
Tentacles pull the prey into the mouth
Digestion happens in the body cavity
Waste is expelled back out through the mouth

7. Movement
Cnidarian movements are directed by nerve cells that spread throughout the cnidarians body like a basketball net
Jellyfish swim through water
Hydras can be found in freshwater and turn somersaults or use their tentacles to move
Watch these Hydra Movies
Sea anemones stretch out, shrink down, and bend slowly from side to side

8. Reproduction Asexual Sexual
Budding is most common in hydras, corals, sea anemones where these polyps just pull apart forming two new polyps.
Sexual
Can occur during the life cycle of certain cnidarians such as the jellyfish

9. Life Cycle of A Jelly Fish

10. Life on a Coral Reef
Coral polyps produce a hard, stony skeleton around its soft body once attached to a hard surface.
Coral polyps then continue to reproduce asexually
Over time, reefs build up from the sea floor and make great homes for other sea life

11. Video Quiz Watch the following clip:
Coral Ecosystems (5:59)
There will be a short video quiz following the clip.
Make sure to take good notes! You can use your notes for the video quiz!