endosymbiosis hypothesis leading to the protist grouping

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)