KINGDOM PROTISTA “The Junk Drawer” of Classification.

KINGDOM PROTISTA

“The Junk Drawer” of Classification

• Classified based on what they are NOT – they are NOT fungi, plants, or animals, but they are eukaryotes (in fact, they were probably the FIRST of the Eukarya)

• Most are unicellular & microscopic

• Groups (phyla) are based on physical characteristics (such as motility) and nutritional characteristics (heterotroph/autotroph)

• First to reproduce sexually; first multicellular organisms

• Live where ever there is moisture

• Historically, divided into algae (plant-like) and protozoa (animal-like)

Rhizopods

Ex) Amoeba

• Flexible surface, no cell wall, pseudopodia

• Heterotrophs – engulf prey with pseudopodia; endocytosis/phagocytosis

nucleus

pseudopodia

Amoeba engulfing a paramecium with pseudopodia – An example of phagocytosis (a form of heterotrophy)

Heliozoans and Radiolarans

* Related to amoebas – pseudopodia & phagocytosis

Note the long, slender pseudopodia coming from the heliozoan on the left

Heliozoans are freshwater; radiolarans are marine

Both form the ooze on the floor of these bodies of water with the shells left from their dead bodies

Foraminiferans – another organism related to the amoebas; note the long pseudopodia coming out of the shell of calcium carbonate

- compose sedimentary rock

- both heterotrophic and photosynthetic (depending on the species)

Euglenoids/flagellates

Example – Euglena

• Called flagellates because of their mode of motility

• Have an eyespot for phototaxis

• Have a contractile vacuole for water balance

• Autotrophic/photosynthetic (look at the chloroplasts!) AND heterotrophic

Trypanosoma – genus of the protist that causes African sleeping sickness in humans (host) following the bite of the tsetse fly (vector)

Closely related to the euglenoids because they have similar body coverings.

Giardia – genus of another flagellated protist that causes

disease in humans

Ciliophora - ciliates

Example - Paramecium

All members of this group

have cilia. Note there are even cilia lining the oral groove

*Have a contractile vacuole

*Have micro and macro nuclei

*Heterotrophic – food enters through oral groove, food vacuole forms, lysosomes help digest food

LOOK! Waste leaving cell via exocytosis

FYI – Not in your notes

Another look at Ciliophorans:

Stentor and Paramecium

Dinoflagellates

Planktonic, photosynthetic protists – called phytoplankton (phyto = plant) AND heterotrophic species as well

Responsible for red tide (named for the photosynthetic pigment they contain); “blooms” of these organisms cause massive fish deaths due to the toxins they produce

Heterotrophic species use the toxins to stun prey (like fish) and then feed on its body fluids

DiatomsAnother group of protists (actually related to water

molds and golden & brown algaes)

Shells made of silica house the photosynthetic organism inside

The shells are in two parts, fitting together like a shoe box or Petri dish

The Algae

Algae – collective term referring to all of the photosynthetic, plant-like protists; alga – singular; algal – adjective

• Multicellular

• Photosynthetic – the algae along with other photosynthetic protists are the largest group of producers on Earth, producing 1/3 of the oxygen

Algae rocks.Chuck knows.

Algae

Have a variety of pigments, on which the name of each group is based (remember, -phyta means “plant”)

• Golden algae – Chrysophyta; related to diatoms

• Brown algae – Phaeophyta; “seaweed”; also closely related to the diatoms; kelp

• Red algae – Rhodophyta; includes some “seaweeds” but not all. Form a separate group from the golden & browns algaes and the green algae; some species are heterotrophic

• Green algae – Chlorophyta; “seaweeds”; have chlorophyll similar to plants; gave rise to the plant kingdom

Volvox (microscopic)

Water MoldOomycota – heterotrophic protist commonly found in very wet environments growing on dead or decaying organisms, such as on the fish below; called “mycota” because they look like fungi (but they’re NOT)

- late blight, a water mold, was responsible for the Irish potato famine

Slime MoldsProtists that aggregate in times of stress to form spore-producing bodies

• Heterotrophic

• Look like fungi but are NOT

Sporozoans

Protists that are:• Nonmotile *Unicellular

• Parasitic *Spore-forming

• Disease-causing*Heterotrophic

Diseases caused include:

• Malaria (host – vertebrates; vector - mosquito)

• Toxoplasmosis (host – humans & cats)

• cattle tick fever (host – cattle, mice, humans, deer, dogs)

• Cryptosporidiosis (host – cattle humans, birds, deer, dogs, cats)

Malaria sporozoans of genus Plasmodium