Kingdom Protista

Very diverse and unique group of organisms. Unicellular and Eukaryotic. Some are autotrophic (photosynthesis), some are heterotrophic. Some are decomposers. Some are parasitic. It is thought that protists are the common ancestors of the other three eukaryotic kingdoms, making it very difficult to classify these organisms.

Protista Cladogram

Three Groups of Protists Animal-Like Protists Plant-Like Protists Fungus-Like Protists

Animal-Like Protists Also called Protozoans Heterotrophic Classified by their method of movement ◦Amoebas ◦Zooflagellates ◦Ciliates ◦Sporozoans

Amoebas “Blobs” of cytoplasm. Move and eat using pseudopodia (“false feet”). Some cause parasitic diseases: ◦Amoebic Dysentery (Entaemoeba histolytica) ◦Brain-Eating Amoeba (Naegleria fowleri)

Zooflagellates Protists that move via a flagellum. Some live in the guts of termites, helps them to digest cellulose Some cause parasitic disease: ◦Dysentery (Giardia lamblia) ◦African Sleeping Sickness (Trypanosoma brucei)

Ciliates Protists that move via cilia. Definite shape determined by pellicle (stiff- flexible membrane) Uncommon to be parasitic. Example: ◦Paramecium

Sporozoans No mode of locomotion. Transferred to hosts via their vector. All species are parasitic: ◦Malaria (Plasmodium falciparum)

Plant-Like Protists Also called plankton – give us 90% of our O 2 ! Autotrophs (photosynthesis) – They have chloroplasts! Most are unicellular (only instance of multicellular protist) and some are colonial. Four different classifications: ◦Dinoflagellates ◦Diatoms ◦Euglenoids ◦Algae

Dinoflagellates Have 2 flagella and spin through the water. Bioluminescent – red in color. Also called fire algae. Produce a toxin that kills fish and people, shellfish are unaffected.

Diatoms Lack flagella and glide through water. Come in many shapes, sizes, colors. Stiff outer shells are made of silica, a glass-like substance. When they die, shells do not decompose (Cliffs of Dover). Used in chalks, toothpastes, cleaning products.

Euglenoids One or more flagella. Grow in stagnant water. Eyespot – sensitive to light. Example: Euglena

Algae Thought to give rise to modern plants. Three types: ◦Green Algae (Chlorophyll A and B) ◦What we know as floating algae. ◦Unicellular, but colonial. ◦Brown Algae (Chlorophyll C) ◦Floating Seaweed. ◦Multicellular. ◦Red Algae (Chlorophyll A and Phycoerythrin) ◦Sea Floor Seaweed. ◦Multicellular.

Fungus-Like Protists Found in cool, shady, moist places. Heterotrophic (decomposers) All are colonial. Two classifications: ◦Water Molds ◦Slime Molds

Water Molds Live only in wet places (freshwater, bathroom showers) Can spread, but do not move. Some species are fish parasites. Caused the Great Potato Famine in Ireland in the 1800s.

Slime Molds Found in moist places. Colonial and can move. Digest organic material in forests.

Reclassification Evolutionary history of Protista is difficult to pinpoint. Molecular evidence supports reclassification.