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?

The importance of protists Section 21.3

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

What do these have in common?

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

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

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

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

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

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

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)

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

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

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?

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

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?

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)