Protists

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Protists often play the role of symbiont or producer.

Some protist symbionts ++ benefit their hosts

Dinoflagellates nourish coral polyps that build reefs.

Hypermastigotes digest cellulose in the gut of termites.

Slide 49

Protist Symbiont ++

10 µm

Slide 50

Some protists are parasitic + - symbionts

Plasmodium causes malaria.

Pfesteria shumwayae is a dinoflagellate that causes fish kills… toxic red tides

Phytophthora ramorum causes sudden oak death.

Slide 51

Risk Map for the Parasitic Protist Sudden Oak Death in United States

Key

Moderate risk

High risk

Low risk

Nurseries with P. ramorum infections (2004) on

other host plants (such as rhododendron).

Slide 52

Photosynthetic Protists

Many protists are important producers that obtain energy from the sun.

In aquatic environments, photosynthetic protists and prokaryotes are the main producers.

The availability of nutrients can affect the concentration of protists.

Slide 53

Protists are Key Producers in Aquatic Communities

Other

consumers

Herbivorous

plankton

Carnivorous

plankton

Bacteria

absorbed by

Soluble

organic matter

secrete

Protistan

producers

Slide 54

Review

Slide 55

You should now be able to:

Explain why the kingdom Protista is no longer considered a legitimate taxon.

Explain the process of endosymbiosis and state what living organisms are likely relatives of mitochondria and plastids.

Distinguish between endosymbiosis and secondary endosymbiosis.

Name the five supergroups, list their key characteristics, and describe some representative taxa.