Protists - Kingdom Protista

Readings on protists:

In addition to your text I highly recommend the following article:

http://web.archive.org/web/20020815115539/www.animalnetwork.com/fish2/aqfm/1999/feb/wb/default.asp

1. Extremely diverse group

• Defined as single-celled eukaryotes
• All the eukaryotes other than the animals, fungi, and plants

-The different protist groups not closely related to each other

(and some of the algae are not even single-celled!)

• Some are photosynthetic (e.g., the plant-like algae) - 40% of global primary productivity!
• Some are heterotrophic and very much like tiny animals
• Some are animal-like but are also photosynthetic

Here we will be covering some of the animal-like protists

(for the plant-like protists click here --> Algae)

• Often very large cells - may be visible to naked eye!
• Very complex cells
  • organelles
  • complex cytoskeleton

3. Means of locomotion

• Amoeboid movement - flowing extensions (psuedopodia) protrude outward, cytoplasm and organelles flow into pseudopodia
  • (most likely the inspiration for the movie "The Blob")
• Flagella or Cilia (generally either flagella or cilia, not both on a given cell)
  • Flagella -long, few per cell, whip-like undulations
  • Cilia - short, many per cell, stiff oar-like motion
  • 

  Electron micoscope view of the cilia in the oral region of Blepharisma, a large freshwater ciliated protist.

  4. Live in all habitats, but most diverse and abundant in fresh and salt water.

• many are free-living
• many are parasitic

5. Feeding styles

• Dissolved organic compounds
• Food particles or prey - intracellular digestion

......

• Photosynthesis (sometimes along with food comsumption)

6. Reproduction

• Clonal, asexual fission
• Sexual reproduction (but typicallythere are not males and females)
• Many can form drought and cold tolerant cysts

7. Diversity - a quick look at just a tiny bit of the tremendous diversity of protists:

• Euglenozoa - free-living flaggleated cells, some are photosynthetic

• Kinetoplastida -mostly parasitic species (e.g. Trypanosomes, which cause African Sleeping sickness, spread by Tsetse flies)

This diagram shows a trypanosome dividing

• Chlorophyta - the green algae (discussed on Algae page)

• Choanoflagellata - sister taxon of the animals, often colonial and sessile

• Alveolata - e.g. the dinoflagellates - mostly photosynthetic, but some are parasitic (see Algae page)

• Ciliophora - the ciliates

Also see http://www.augsburg.edu/home/biology/photoofmonth/damselnymphvort.html for cool photos of some stalked ciliates similar to the one in the diagram above.

• Sporozoans - parasites, complex life cycles, Plasmodium is an example (causes malaria)

• Amoeboid protozoans
  • Amoebas

  

  • Foraminiferans - essentially amoebas that live in shells, some are huge cells (e.g., some are the size of a pea!).
    • See http://www.imagequest3d.com/pages/articles/articleofmonth/foraminifera/foraminifera.htm for additional photos.
    • See http://reefkeeping.com/issues/2003-07/rs/index.htm for more information and more photos

  

  • Slime molds

Click here for the Algae