Kingdom Protista

The most diverse group of organisms

Discovery of Protists• Anton van Leeuwenhoek– Lived around 300 years ago– First to use a microscope to

see cells

– “No more pleasant sight has met my eye than this of so many thousands of living creatures in one small drop of water.”

What can you find in a single drop of water??

Evolution of Protists

• Evolved from prokaryotes 1.5 billion years ago• Protists are the first known eukaryotic

organisms• They would lead to the evolution of fungi,

plants and animals

What is a protist?• A eukaryote that cannot be classified as fungi, plant or animal

• An organism that has very diverse characteristics

• A microscopic organism that lives in water

• Can be grouped into two general categories:– Protozoa– Algae

How many cells?? (It depends!)

• Most protists are unicellular, but some are multicellular

• Some are colonial– each individual has a specific number of cells– all individuals together make up the colony– the colony acts like a multi-celled organism

Volvox Colonies

• http://video.google.com/videoplay?docid=-3471807967695834419

What is their function? (It depends!)

Some are…• Producers– many protists are photosynthetic and are major

contributors to the Earth’s oxygen atmosphere• Consumers– some protists eat other organisms for energy

• Decomposers– some breakdown dead organisms to return

nutrients to the soil

The Protozoa Blues

• http://video.google.com/videoplay?docid=3578205676570425677&q=protozoa+site%3Avideo.google.com&total=13&start=0&num=10&so=0&type=search&plindex=2

Protists: The 411

1. All are Eukaryotes2. All are aerobic (require oxygen)

3. All have mitochondria4. All live in water-based environments

(fresh water, oceans and seas, damp soil, snow)

5. Some have chloroplasts6. Some reproduce asexually, some sexually

3 Main Types

• Plant-like protists

• Animal-like protists

• Fungus-like protists

Plant-like Protists (AKA algae)

• Algae are protists that are strictly photosynthetic• Algae are distinguished by the type

of photosynthetic pigment they contain• Algae are also classified based on

their cell or body shape

Green Algae – Phylum Chlorophyta

• Most are found in freshwater

• Major part of plankton (small organisms found on the surface of a body of water)

• Contain chloroplasts and undergo photosynthesis

Biscayne Bay – Miami, FL

Brown Algae – Phylum

Phaeophyta• Multicellular• Found in marine and

coastal regions• Examples: kelp, seaweed• Can be up to 30 m long• Provide protection and

shelter for many coastal fish

Red Algae – Phylum

Rhodophyta

• Multicellular• Found in tropical

zones and deep ocean regions

• Able to absorb light that penetrates deep waters

Caloosahatchee River, SE Florida(Gulf of Mexico side of Florida)

Diatoms – Phylum

Bacillariophyta

• Unicellular• Cell wall contains silica

(mineral found in glass)• Double shell (fits

together like the bottom and top of a shoe box)

• Their shells are used to make reflective paints

Dinoflagellates – Phylum Dinoflagellata

• Have 2 flagella• Huge increases in

population cause red tides = fish are killed due to less oxygen in the water, water looks red due to overpopulation

• Most are found in saltwater

Euglenoids – Phylum Euglenophyta

• One flagella

• Eyespot – light sensitive organ that tells the organism to move toward light

• Found mostly in freshwater

Animal-like Protists (AKA protozoa)

• Classified based on their type of nutrition• Ingest their food by endocytosis (engulfing

food into the cytoplasm)

Paramecium – Phylum Ciliophora

• Move by beating tiny hair-like structures called cilia

• The cilia act in unison like oars on a boat• Have one large contractile vacuole for water

and waste storage

Amoebas – Phylum Rhizopoda

• Move by pseudopodia(false feet)

• Amoebas can live in water, soil or living organisms

Sporozoans – Phylum

Apicomplexa

• All parasites• Transmitted

through blood-eating insects or feces

Malaria• One of the most deadly diseases in humans• Caused by a protist called plasmodium• A mosquito bites an individual and the protist is

injected into the blood stream• Over 100 million people have malaria• Up to 3 million people, mostly children, die from it

every year

• Symptoms include severe chills, fever, sweating, and confusion

• Victims typically die of other related complications including anemia, kidney failure or brain damage

• Malaria and fake drugs: http://video.google.com/videoplay?

docid=8997083794746163547&q=malaria&total=1547&start=0&num=10&so=0&type=search&plindex=3 (first 10 minutes)

Fungus-like Protists (AKA molds)• Two groups– Plasmodial slime molds• Phylum Myxomycota• Look like oozing slime• Absorb bacteria and nutrients as they slowly move

– Water molds• Phylum Oomycota• Usually feed on dead material • Responsible for the potato famine in Ireland (1845-

1850) that killed almost 1 million people