• Protists: Unicellular eukaryotic organisms.

• Over 115,000 species

• Eukaryotic cells - contain membrane-bound organelles (particularly mitichondria & chloroplasts)

• Protists & eukaryotes probably evolved from a large eukaryotic cell ingesting a photosynthetic and oxygen metabolizing bacteria
• Known as endosymbiotic theory
• Three major classes of protists

1. Animal-like protists
2. Plant-like protists
3. Fungus-like protists

Phylum Ciliophora (Cilia bearing protists)

• Aka "ciliates"
• Have cilia (short hairlike structures) on their plasma membranes
• Cilia rapidly beat and provide propulsion for the protist.
• Over 7000 species in this phylum.
• Example is paramecium.

• Large organisms ~305 micrometers long
• Important features:
• Have 2 nuclei
• Macronucleus (large)
• Micronucleus (smaller)
• Feed by forcing H2O into Gullet forming food vacuoles
• Excrete wastes through anal pore
• Excrete excess water through use of contractile vacuoles.

Phylum Sporozoa

• Usually parasitic in nature
• Example is Plasmodia which causes malaria.
• Malaria is transmitted by the Anopheles mosquito.
• Spores infect liver cells
• Liver cells lyse releasing plasmodium cells which infect blood cells

Plasmodia Lifecycle

Plasmodia inside liver cell

Phylum Sarcodina (Protists with false feet)

• .

Plant-like Protists

• 5 phyla of plant-like protists.
• All are unicellular, most are motile
• Most are photosynthetic and heterotrophic

Single Cellular Algae

• Are all photosynthetic
• Lack advanced plant tissues since they are unicellular
• Major source of organic molecules and O₂ for the planet.

Examples:

• Dinoflagellates
  • Have 2 flagella for motility
  • Often have a cellulose covering 

• Diatoms

  • Most abundant form of marine algae.

  • Form elaborate silicon (glass) shells to protect themselves

  • Shell is porous to allow materials in/out of the cell.

Diatoms

• Phylum Euglenophyta
  • Example is euglena.
  • Has a flagellum, is motile
  • Is both heterotrophic & autotrophic
  • Contains chloroplasts & is photosynthetic.
  • Can become heterotrophic in low-light conditions

euglena

Multicellular Algae

• Are not generally true multicellular organisms, but rather "colonies"

• Show beginnings of specialized functions / tissues

• 3 types

  • Green algae (Chlorophyta)

    • contain chlorophyl a & b

    • Most frequently found in fresh water

    • Often colonial

    

    Volvox (colonial green algae)

  • Red Algae (Rhodophyta)

    • Found in salt/brackish water

    • Have additional pigments which give them a reddish color.

    • In uncontrolled blooms, these organisms can cause serious ecological damage

Red Algae 

• Brown Algae (Rhodophyta)

  • Most Plant-like of all algae.

  • Include kelps

  • Can grow to huge sizes (100')

  • Most primitive plant like organism to show alternation of generations.

  

  Kelp forest