1. Phylum Cnidaria & Ctenophora
Kingdom: Animalia
Phylum Cnidaria
Class Hydrozoa
Class Scyphozoa
Class Anthozoa
Phylum Ctenophora

2. Major Characteristics
Presence of specialized tissues
Also called Coelenterates
Comprised of sea anemones, jellyfish, corals
Have radial symmetry
Two forms polyps and medusa

3. Body Structure
All have radial symmetry, where similar parts of the body are arranged and repeated around a central axis

4. Radial vs. Bilateral Symmetry
Diagram A

5. Radial Symmetry

6. Two Main Body Forms - Polyp
A polyp is a sac like stage.
Sessile or non-motile

7. Two Main Body Forms - Medusa
A medusa is bell-like, which is similar to an upside down swimming polyp
Free floating or swimming

8. Polyp vs. Medusa
Some spend their life as both at some point or as one or the other the entire time
Diagram B

9. Polyp vs. Medusa
Diagram D

10. Three Basic Layers:

11. Three Basic Layers
Ectoderm/Epidermis – outer layer that contains the stinging cells
Endoderm/Gastrodermis – lines the gut
Mesoglea – Jelly like substance in between the Ectoderm and Endoderm which contains scattered cells and collagen fibers

12. Exoskeleton
Coral will create a calcium carbonate shell in which it will live

13. Body Structure
The mouth is located on the top of the polyp or underside of the medusa
It is the only opening on the organism so is also shares the function of being an anus
Diagram E

14. Body Structure
Diagram F

15. Tentacles
Slender finger like structure used to capture and handle food
Location of nematocysts

16. Nematocysts
The main characteristic of Cnidaria is the presence of nematocysts
Stinging structures found on the tentacles

17. Nematocysts Coiled – like stinger
Spring into the prey and releases toxin
Most not harmful to humans because they cannot penetrate skin
Some fatal

18. Nervous System Main characteristic is the presence of a nerve net
Nerves cross over each other, at every connection, communication occurs
In humans millions cross over millions and no communication occurs

19. Nerve Net
Diagram C

20. Digestive System All cnidarians are carnivorous
Paralyzed by the nematocysts
Enzymes in gastric cavity break down the food and nutrients are absorbed by cells in the endoderm
Wastes are sent out the mouth/anus

21. Digestive System

22. Reproductive
Cnidarians have the ability to reproduce sexually and asexually
One method that is commonly seen is budding

23. Class Anthozoa Largest group of Cnidarians
Stay in the polyp stage throughout life cycle
Solitary or colonial
Includes sea anemones

24. Class Hydrozoa
Can consist of just a polyp stage, just a medusa stage, or both
Can join together to form complex colonies such as the Portuguese Man-O-War, which develop floats
FLOAT

25. Class Scyphozoans BELL Medusa is the dominant life stage
Swim with rhythmic contractions of the bell, though limited
Contain the most dangerous/fatal stings
BELL

26. Phylum Ctenophora Comb Jellies
Not a member of the Cnidarian Phylum even though they share similarities

27. Cnidaria vs. Ctenophora
Have cilia at the base of the medusa to move
Engulf food
Do not have nematocysts
Have an additional layer between endo and ecto layers
Anal pore