Kingdom Protista

Protists

Protists belong to the Kingdom Protista, which include mostly unicellular organisms that do not fit into the other kingdoms.

Characteristics of Protists

  • mostly unicellular, some are multicellular (algae)
  • can be heterotrophic or autotrophic
  • most live in water (though some live in moist soil or even the human body)
  • ALL are eukaryotic (have a nucleus)
  • A protist is any organism that is not a plant, animal or fungus

Protista = the very first

Classification of Protists

  • how they obtain nutrition
  • how they move

Animallike Protists – also called protozoa (means “first animal”) – heterotrophs
Plantlike Protists – also called algae – autotrophs
Funguslike Protists – heterotrophs, decomposers, external digestion

Animal-like Protists: Protozoans

Four Phyla of Animal-like Protists -  Classified by how they move

  • Zooflagellates – flagella
  • Sarcodines – extensions of cytoplasm (pseudopodia)
  • Ciliates – cilia
  • Sporozoans – do not move

Zooflagellates

move using one or two flagella
absorb food across membrane
Ex.  Leishmania

Sarcodines

Ameba See Ameba Coloring Sheet

moves using pseudopodia ( “false feet” ), which are like extensions of the cytoplasm –ameboid movement
ingests food by surrounding and engulfing food (endocytosis)
, creating a food vacuole
reproducing by binary fission (mitosis)
contractile vacuole – removes excess water
can cause amebic dysentery in humans – diarrhea and stomach upset from drinking contaminated water
Other sarcodines: Foraminferans, Heliozoans

Video:  Ameba Proteus

Ciliates

Paramecium (See Paramecium Coloring Sheet)

move using cilia
has two nuclei: macronucleus, micronucleus
food is gathered through the :mouth pore, moved into a gullet, forms a food vacuole
anal pore is used for removing waste
contractile vacuole removes excess water
exhibits avoidance behavior
reproduces asexually (binary fission) or sexually (conjugation)
outer membrane -pellicle- is rigid and paramecia are always the same shape, like a shoe


Pond Life Videos

Sporozoans

do not move on their own
parasitic
Malaria is caused by a sporozoan  (Plasmodium), which infects the liver and blood; transmitted by mosquitos