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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