Each of the 7 major groups of eukaryotes contain protists

Contractile Vacuoles expel water from the cell

Single celled organisms are usually much more complex that multi-cellular organisms because they have to do all the same basic jobs but they only have one cell to do it with.

-Swimming via flagella

-Swimming via cilia

Protists patterns of nutrition

  • Autotrophic (Algae- plant like)
  • Heterotrophic
    • Ingestors (protozoa; animal-like)
    • Absorbers (Slime mods; “fungus-like”)
  • Mixotrophic
    • nutritionally flexible organismss; can be both
      photosynthetic and heterotrophic


  • Lack cell walls and take in food by engulfing it
  • Move via amoeboid motion and produce large, lobe-like pseudopodia
  • Amoebae are abundant in freshwater habitats and in wet soils
    • Some are also parasites of humans and other animals
  • Major subgroups in the lineage are lobose amoebae, cellular slime
    molds, and plasmodial slime molds


Pseudopodia engulf food

-Entamoeba histolytica– causes amoebic dysentery

-Plasmodial slime molds are important decomposers in forests

Opisthokonta: Choanoflagellates

  • Many are colonial, ancestors of metazoans

Excavata: Parabasalids, Diplomonads, and Euglenids

  •  Includes free-living, mutualistic, and parasitic species
  • Are all single-celled
  • Most swim using their flagella

Giardia intestinalis

  • Causes intestinal infections in humans


  • the kinetoplastid that causes sleeping sickness

Plantae– Green Algae

Alveolata: Ciliates, Dinoflagellates, and Apicomplexans


  • Ciliates were named for the cilia that cover them and that they use for locomotion
  • Diverse group- All of the known 12,000 ciliate species live in freshwater habitats, marine environments, and wet soils
  • Large complex cells

Trichocysts are a type of extrusome: organelles capable of ejection


  • Have 2 flagella, at least one of these surrounds the cell in a groove in the center.
  • Cell wall is composed of interlocking plates, usually of cellulose.
  • Important primary producers in ecosystems

The Zooanthellae are important dinoflagellates that are endosymbiotic in corals and other cnidarians, as well as other organisms.