1. Chapter 9.3 Sponges and Cnidarians

2. POINT > Describe characteristics of sponges
POINT > Describe characteristics of a cnidarians
POINT > Describe two stages of cnidarian life cycle
POINT > Emphasize the importance of coral reefs

3. POINT > Describe the characteristics of sponges
Sponges are the simplest animals
Cellular level of organization (no tissues or organs)
No symmetry
Live in fresh and salt water
Water flows in through the cells and out through the top.
Single-celled organisms are filtered out of the water for food

4. POINT > Describe the characteristics of sponges
Choanocytes are cells that move water through the sponge
Sponges reproduce both asexually and sexually

5. CHECK:
What kind of symmetry do sponges have?
What level of organization to sponges have?
What are choanocytes?
Where do sponges live?

6. POINT > Describe characteristics of cnidarians
Cnidarians include jellyfish, hydra, anenomes and corals

7. POINT > Describe characteristics of a cnidarians
Cnidarians have radial symmetry
Tissue level of organization: simple nervous and muscle tissue
Have stinging cells called nematocysts for capturing prey
Have a mouth and digestive cavity to eat prey
Reproduction is both sexual and asexual (budding)

8. POINT > Describe two stages of cnidarian life cycle
Cnidarians have a two-stage life cycle:
1. Polyp – lives attached to rock or lake bed

9. POINT > Describe two stages of cnidarian life cycle
Cnidarians have a two-stage life cycle:
2. Medusa – free swimming

10. POINT > Describe two stages of cnidarian life cycle

11. CHECK:
What type of symmetry to cnidarians have?
What are 3 types of cnidarians?
What are the two stages in cnidarian life cycles?
What are nematocysts?
What are 4 characteristics of animals?
What type of vascular plant does not have seeds?

12. Polyp or medusa?

14. Coral reef

15. POINT > Emphasize the importance of coral reefs
Corals are cnidarians that live in colonies
Coral reefs are made of the dead skeletons of the coral
Coral reefs provide habitat for fish and other organisms in the oceans
Most of the oceans’ biodiversity exists in coral reefs

16. POINT > Emphasize the importance of coral reefs
Coral reefs are being destroyed rapidly by pollution, over-fishing and increases in water temperatures and acidity
Large reefs in the Caribbean and South Pacific ocean have experienced 40-90% loss over the past 10 years

17. Homework: Read pages
Section Assessment Page 311 #1-3
GRAS Pages