1. Phylum Cnidaria

2. General Characteristics
About 9000 species
_____________________
Simple nervous system
__________________
Diploblastic organization
Endoderm
Ectoderm

3. General Characteristics Cont’d-
Either tubular or bell shaped
_______________________
Only animal with
cnidocytes
Cnidocytes-specialized
stinging cells (on tentacle)
All marine (aquatic)

4. ____________________________
Cnidarians’ bodies are organized around the gastrovascular cavity, where digestion takes place
GV has a single opening that serves as both mouth and anus

5. Gastrodermis: lines GV cavity
2 Layers of Cells
Diploblastic:
__________________________
Gastrodermis: lines GV cavity
Epidermis: lines the outside of the body (the skin)

6. In between the two layers is the _________- a jelly-like substance.

7. Cnidarian Body Wall

8. Stinging Cells Have Cnidocytes ________________
Contain nematocysts: barbed thread-like structures inside the cnidocyte that shoots out and can puncture and poison or entangle prey

9. Cnidocyte

11. Feeding _______________________________
Inner gastrodermis secretes digestive juices into gastrovascular cavity which digests food and circulates nutrients

12. Feeding Cont.

13. Nervous and Movement
_________________ & sensory receptors
Muscles help in directional movement
& capturing prey

14. _______ Medusa Life Cycles
Cnidarians have two body forms that are representative of the sexual and asexual life cycles that they undergo.
_______
Medusa

15. Polyp _______ Usually attaches to a substrate at the aboral end
Oral end is surrounded by feeding tentacles

16. Medusa _________ ________________ Sexual (dioecious)
Shaped like an upside-down bowl
Tentacles surround the mouth that is housed underneath the bell

17. When cnidarians display both forms at some point in their lives, they are said to display an __________________________

18. _________________________
Both sexual and asexual
Sexual
Gametes released into water
Fertilization takes place to create free-swimming planula
Asexual
By budding

19. Generalized Cnidarian Life Cycle

21. __________________________
Scyphozoa: Jellyfish
Anthozoa: Sea anemones & Corals
Hydrozoa: Hydra
Cubozoa: Box Jellies

22. Class Hydrozoa
Ex. Hydras

24. __________________
Includes hydras, fire corals, and Portuguese Man of War
Display alternation of generations
Polyp
Medusa

25. Class Scyphozoa
True Jellyfish
___________________________
Small polyp stage during life cycle

26. _____________________
Similar to Scyphozoans, except that their medusa is cuboidal
Includes the box jellyfish
1 of the 10 most venomous animals on the planet
Kills 12 people per year

28. Class Anthozoa
Polyps that are flower-like
___________________
Includes sea anemones, corals, sea whips, and sea fans