1. Phylum Cnidaria

2. Do Now
Observe the sea anemone and jelly fish. Write down characteristics you see or any you already know of.

3. Target Goal

4. Video: Jellyfish Scene from Nemo

5. Phylum Cnidaria Vocabulary
Polyp
Medusa
Cnidocyte
Nematocyst
Gastrovascular cavity
Extracellular
Spawning

6. Cnidarians - jellyfish, coral, hydra, sea anemone
*Named after the stinging cells found on their tentacles called CNIDOCYTES

7. Cnidarians have two body forms:
polyp (vase shaped)               medusa (cup shaped)

8. Portuguese Man of War - cnidarian that floats in the water and has long tentacles

9. Coral Reefs are made from the skeletons of cnidarians

10. General Characteristics
Symmetry:
Radial
First animals with real specialized tissues
3 Body Layers:
Ectoderm-outer layer
Mesoglea-loose jelly-like layer
Endoderm-inner layer
Gastrodermis aka
Gastrovascular cavity

11. Specialized Cells: Cnidocytes
Stinging cells, found on tentacles
Nematocyst
Barbed thread within the cell
To capture prey or self- defense

12. What kind of symmetry do cnidarians have?
Question Time!
What kind of symmetry do cnidarians have?

13. Name the 3 tissue layers of cnidarians.

14. The stinging cells on cnidarians are called. a. nematocysts. b
The stinging cells on cnidarians are called a. nematocysts b. cnidocytes c. tentacles

15. 2 Body Forms Medusa Polyp
Free-flowing
Jelly-like
Umbrella shaped
Polyp
Tubelike
Attach to an object
In both forms there is a fringe of tentacles around the mouth
Some Cnidarians exist only in one body form, others alternate between the 2 body forms

16. Hydra Anatomy WORD BANK Gastrovascular cavity Tentacle Cnidocyte
Ectoderm
Endoderm
Mesoglea
Ovary/Teste
Bud
Nematocyst
Mouth
Basal Disk

17. Life Processes Digestion:
Begins extracellularly, in the gastrovascular cavity
Enzymes break food down into fragments
Cells then engulf the fragments
Digestion is then completed intracellularly

18. Life Processes Respiration:
Oxygen and Carbon Dioxide are exchanged by diffusion
Nervous System:
Nerve cells form nerve nets
Little coordination is present

19. Life Processes Support and Locomotion:
Water is contained under pressure in the gastrovascular cavity
Reproduction:
Asexual
Fragmentation- sea anemone pull themselves in half
Budding-Hydra
Sexual
External Fertilization
Hermaphrodites
Spawning

21. Class Hydrozoans Freshwater: Example-Hydra Only exist as Polyps
Stick to rocks or plants with a material they secrete from their basal disc
Are able to flip their bodies and move

22. Class Hydrozoans-use both body forms
Marine:
Can form colonies but are not interdependent
Example-Portuguese man-of-war (Physalia)
Float on the surface of the water
Their tentacles dangle and can reach 60 m long
Used to stun and entangle prey
Nematocysts have a powerful neurotoxin that may kill humans
Example-Obelia
As polyps they may bud
Those buds can take a medusa form as a male or female
The medusa produces gametes
An embryo is created
The embryo becomes a larvae called a planula (w/ cilia)
That planula settles on the ocean floor and becomes a polyp once again

24. Class Scyphozoa Referred to as true jellyfish
Active predators that ensnare and sting their prey
Size range goes from a thimble to a queen sized mattress
Can be polyps at some point in their life cycles
Examples: Aurelia
Has a life cycle like a Obelia
One difference is that most of the life cycle for the Aurelia is in the medusa stage

25. Class Anthozoans Largest classes Exist only as polyps
Contain a symbiotic algae
Dinoflagellates
Cause brilliant colors
Reproduce asexually with budding
Reproduce sexually by
1. Releasing eggs and sperm into the ocean
2. Fertilization occurs planulae settle and develop into polyps

26. Class Anthozoans Example: Sea Anemone Soft-bodied polyps
Found in coastal areas
Feed on fish and other marine life
Highly muscular and complex
Asexual-pulling apart
Example: Coral
Live in colonies called reefs
Some have soft bodies
Many secrete a tough outer skeleton made of calcium carbonate
Only the top layer is living
When they die their skeleton remains and is a foundation for the new generation
Found in tropical regions

27. Jellyfish relatives: Class Cubozoan Box Jellies, sea wasp
A polyp phase in their life cycle has never been observed
Most are between 1 cm and 25 cm
Live in the tropical northern coast of Australia
Phylum Ctenophora
Comb Jellies
Only have a medusa phase
Have no cnidocytes
Instead they have a sticky substance that traps plankton
Many are small but their tentacles can be 10x the length of their bodies

28. Videos Long Jellyfish Video http://www.youtube.com/watch?v=9HMLVQipn7s
Sea Anemone
Sea Anemone and Jellyfish
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Cnidarian Reproduction and Nematocyst method