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Endosymbiosis Hypothesis Leading to the Protist Grouping
4 Basic Groups of Protists
• Algae (plant-like protists)
• Protozoans (animal-like protists)
• Slime molds (both fungus-like protists)
• Water molds
Kingdom Protista
• eukaryotic
• mostly unicellular
• autotrophic and heterotrophic (some can be both at the same time)
• has become the “catch-all” kingdom and is the most diverse structurally
Green Algae
(Chlorophyta)
Chlorophyta
• Mostly aquatic-freshwater and marine, some terrestrial
• May be unicellular, multicellular, even colonial
• Reproduce sexually and asexually
Chlamydomonas: a unicellular alga
Volvox: a colonial alga
Brown Algae
Phaeophyta
Phylum Phaeophyta
• Multicellular• Marine; usually found in colder waters• Body parts include a blade, stipe, and holdfast • Most brown algae contain a mucilaginous material
which prevents them from drying out when they are exposed at low tide; these guys are very tough!
• Of economic importance: used for food (when dried) and as fertilizer (oh, by the way, it’s in ice cream too—look for algin on the ingredient panel!)
Parts of a brown alga
•
Rockweed:a brown alga
www.annapolisriver.ca/. ../rockweed.jpg
Red Algae
Rodophyta
(see page 539 in your text for a great picture of red algae)
http://www.ucmp.berkeley.edu/protista/reds/porphyra.gif
Phylum Rodophyta
• Mostly in warm marine environment
• Multicellular
• Smaller and more delicate that brown algae
• Of economic importance: a source of agar (remember that stuff ?), in cosmetics and in the food industry for thickeners (also used as nori for you sushi lovers)
Golden Algae
Bacillariophyta
(the diatoms)
Bacillariophyta
• Unicellular• The organism sits inside a
shell made of silica• They are major
photosynthesizers due to their sheer numbers
• Serve as a major component to the ocean food chain
• Of economic importance as abrasives, diatomaceaous earth for pool filters
The Dinoflagellates(Alveolata)
Phylum Dinoflagella
Dinoflagellates
• Unicellular• Protected by cellulose
plates• Most have two flagella
one which is used for locomotion
• Some species are responsible for causing “red tides” when the environmental conditions are correct
Red Tides…
The water in Penn Cove (Coupeville, WA) turned orange on 5/8/04 due to a "red tide." Photo courtesy of Mary Jo Adams (copyright 2004).
serc.carleton.edu/ microbelife/topics/redtide/
NJ Department of Fish & Wildlife: Bureau of Shellfisheries
Noctiluca: “Sparkle of the Sea”
Pfiesteria piscicida
Slime molds and water molds
• Have a phase of their life cycle that is amoeboid-this means they can move from place to place. This structure is called a plasmodium.
• During reproduction, the plasmodium produces structures which will produce spores.
• The spores will germinate to produce a new plasmodium.
• Water molds will decompose dead organisms making the body of the organism they are decomposing look “fuzzy”.
Life cycle of a slime mold…
The varied stages of slime molds
Water mold(poor goldfish!)
The Euglenoids
(Euglenophyta)
Phylum Euglenophyta
• Freshwater• Unicellular• Autotrophic and heterotrophic (some can
switch back and forth!-pretty cool, eh?)• Have an eyespot to detect light• Possess a long flagellum for locomotion(This group is a mix of plant and animal
characteristics rolled into one organism!)
The Protozoans(animal-like protists)
• Unicellular (but each cell carries out all of the functions which are performed by specialized tissues in multicellular organisms)
• Motile (this means they can move)• Heterotrophic• Informally divided into groups based on
what they use for locomotion
The animal-like protists…
• Informally divided into groups based on what they use for locomotion:- Cilia (ciliates)- Flagella (flagellates)
- Pseudopods (ameboid protists)
Amoeboids:
• Move by using pseudopods, which are extensions of the cytoplasm
• Feed by engulfing prey whole: phagocytosis
• Possess contractile vacuoles which pump out excess water as it is constantly entering the cell of this organism
Amoeba proteus
Elphidium granti
A foraminifer (foram); (a shelled amoeba)
Uvigerinella californica
Another foram
The White Cliffs of Dover (U.K.)
A deposit of many foram shells!
http://www.ballofdirt.com/media/333/2062/7629.html
Guess what? More forams!!!
Flagellates:
• Move by means of flagella
• Many of these are disease causing to humans causing “hiker’s diarrhea”, African Sleeping Sickness
Giardia lamblia
S.E.M. of Giardia lamblia showing ventral sucker
The Sporozoans: Phylum Sporozoa
• All parasitic
• No method of locomotion as adults
• Examples include the microoorganism that causes malaria: Plasmodium
Plasmodium (malaria) life cycle
The significance of the protists is that
• Ancestors of the land plants have their evolutionary basis in protists
• Ancestors of the modern fungi have their evolutionary basis in protists
• Ancestors of the modern day animals have their evolutionary basis from this group
A charophyte (a green alga) and modern day Elodea
Comparison between a protist and a parazoan (a sponge)