1. Bellwork: What is this. What is a possible cause
Bellwork: What is this? What is a possible cause? What possible impact does this have on an ecosystem?

2. The importance of protists
Section 21.3

3. In today’s class
Evaluate the ecological significance of photosynthetic protists in ecosystems
Identify symbiotic relationships involving protists
Summarize the potential risk that symbiotic protists pose to human health

4. What do these have in common?

5. Not all algae are plants…
Some are prokaryotes
Some are plants
Some are Protists
Including red and brown algae
Euglenas
Dinoflagellates
All are autotrophic – can create energy from the sun
Red algae is autotrophic protist most closely related to plants
Others are closely related to non-photosynthetic protists

6. What roles do photosynthetic protists play in food chains/webs?
They are at the base!
As such, they make much of the diversity of aquatic life possible
Key examples:
Phytoplankton – feeding fish and wales.
Carry out about half of all photosynthesis on Earth!
Supporting coral reefs
Protist algae (zooxanthellae) provide most of a coral reefs energy requirement by photosynthesis
Coralline red algae helps provide calcium to stabilize growing coral reeds

7. Role of autotrophic protists continued….
Providing shelter
Giant kelp – largest known protist
Brown alga that can grow 60m long
Provides shelter and food for many organisms
Recycling wastes
Protists often grow rapidly where sewage is discharged
Help recycle waster nutrients, but numbers can get out of control!
Can lead to eutrophcation
In some cases toxins can build up alongside algal bloom – poisoning fish and shellfish

8. But, not all protists are autotrophic…
Many are heterotrophic
They will engulf and digest their food, while others live by absorbing molecules from the environment
Examples:
Amoebas:
Surround a cell or particles and ’take it in inside’ creating a food vacuole
Material is digested rapidly, and nutrients are distributed throughout the cell
Ciliates:
Paramecium and other ciliates use their cilia to sweep food particles into their gullet
They are subsequently forced into food particles at their base
Fuse with lysosomes that contain digestive enzymes
Waste material fuses with anal pore to be released

9. Slime mold Thrive on decaying matter
Key role in recycling of nutrients

10. Protists that absorb
Some protists survive by absorbing molecules that other organisms have released into the environment
Water mold grows on dead or decaying plants or animals
Food molecules are absorbed through cell walls and membranes

11. What does symbiosis mean
What does symbiosis mean? How do symbiotic relationships relate to protists?
Symbiosis – relationship whereby two species live close together
Can be mutualistic (both organisms benefit)
Example termites can’t digest cellulose in wood – require protist Trichonympha
Can also be parasitic (only one organism benefits)

12. What is the link between parasites and disease?
Some parasitic protists can carry some of the world’s deadliest diseases
Examples – Intestinal disease caused by water borne parasites found in streams, lakes and oceans
Cryptosporidium and Giardia – common examples
African Sleeping Sickness
Caused by protist Trypanosoma, spread from person to person by bite of tsetse fly
Destroy blood cells and infect other parts of body including nerve cells
Severe damage to nervous system can cause deep and sometime fatal sleep

13. Malaria One of the world’s most serious infectious diseases
More than 1 million people dies from malaria each year
Caused by Plasmodium, a spore forming protist carried by the female Anopheles mosquito

14. Writing assignment: What is the potential health risk of swimming in natural swimming holes like Slide rock, or Saguaro lake? Are there any ways that these risks can be mitigated? What steps should state park officials take to ensure that these locations are safe for all visitors?

15. Extension (small extra credit opportunity…)
Research a water borne disease on the center of disease control and prevention website
List major causes, symptoms, treatment and how it can be prevented
Presented your findings to class tomorrow

16. Key points questions
What is the ecological significance of photosynthetic protists?
How do heterotrophic protists obtain food?
What types of symbiotic relationships involve protists?
What human diseases can be caused by protists? How are these diseases spread?

17. Key points summary
Photosynthetic protists form the base of nuermous food chains/webs, and play a significant role in supporting ecosystems, providing shelter and recycling waste products
Heterotrophic protists obtain food throgh either engulfing and digesting (amoeba, ciliates), or absorbing moelcules from their environment (water mold)
Mutualistic symbiotic relationship (example – termite) and parasitic symbiotic relationship (cryptosporidium, palsmodium)
Diseases – Malaria (mosquitos), African sleeping sickness (Tsetse fly), Intestinal diseases (contaminated water)