1. Porifera and Cnidarians

2. Key Questions
Describe the distinguishing characteristics of sponges and cnidarians.
Describe how sponges and cnidarians feed and reproduce.

3. Phylum: Porifera (Sponges)

4. Characteristics: Asymmetrical: no front, back, left or right
No complex organs
Sessile (attached at base)

5. Feeding: A. Sponges are filter feeders http://vimeo.com/40240443

6. B. Choanocytes: Specialized cells that use flagella to move a steady current of water though the cell. C. The movement of water is the mechanism for feeding, respiration, circulation and excretion.

7. Support System
Mineral spicules

8. Reproduction A. Asexual through fragmentation: a piece of sponge can regrow into an adult sponge

9. B. Sexual through spawning: sperm and egg are release
B. Sexual through spawning: sperm and egg are release. Form a free swimming zygote

10. Cnidarians (jellyfish, sea anemone, hydra, coral)

11. Characteristics
A. Radial Symmetry B. Incomplete gut (has a mouth but no anus) C. Jelly-like

12. A. Cnidocytes and Nematocyst
1. Cnidocytes are stinging cells that are located along tentacles 2. Nematocyst is a poison-filled, stinger structure that contains a tightly coiled dart

14. B. Circulation, respiration, and excretion: food and waste are transported throughout the body and out of the body wall through the mouth.

15. III. Support system
A. Hydrostatic skeleton: the water pressure gives the jellyfish its shape

16. B. Polyp: tentacles up

17. Medusa: Tentacles down

18. IV. Reproduction Asexual through budding http://www.youtube.com/watch?v=5gXu-4ABXNA

19. Sexual through spawning http://www.youtube.com/watch?v=oHiVA9J_YIM