1. Protista
Chapter 19

2. Ecology of Protists Protists are of enormous eco-logical importance
Photoautotrophic forms:
Produce oxygen
Function as producers in both freshwater and saltwater ecosystems
Major component of plankton
Organisms that are suspended in the water
Serve as food for heterotrophic protists and animals
Many protists are symbionts

3. Protist Diversity

4. 19-1 World of Protists Objectives
Identify the characteristics of the Kingdom Protista
Compare and contrast the four groups of protozoan

5. Zooflagellates – Phylum Zoomastigophora
Colorless heterotrophs
Most symbiotic and many parasitic
Well known for causing various diseases in humans
Trypanosoma
African sleeping sickness - Tsetse fly
Chagas disease – Kissing bug
Giardia lamblia
Most common flagellate in human digestive tract
Causes severe diarrhea
Cysts are transmitted in contaminated water
Beavers are important reservoir hosts
Trichomonas vaginalis
Sexually transmitted protist,
Infects urogenital organs; a common cause of vaginitis

6. Zooflagellates

7. Giardia lamblia

8. Protists with Pseudopods
Pseudopods form when cytoplasm streams forward in a particular direction
Amoeboids (phylum Rhizopoda) are protists that move and ingest their food with pseudopods
Phagocytize food
Entamoeba histolytica - a parasite of the human colon;
Causes amoebic dysentery
Can be fatal
Foraminiferans (phylum Foraminifera) and radiolarians (phlyum Actinopoda)
Both have a skeleton (test) of either calcite or silica

9. Protists with Pseudopods

10. The Ciliates – Phylum Ciliophora
Ciliates (phylum Ciliophora) are among the most complex of the protozoans
Hundreds of cilia beat in coordinated rhythm
Most are holozoic, swallowing food whole
usually asexual

11. Ciliates

12. The Sporozoans – Phylum Apicomplexa
Nonmotile obligate parasites
Most serious parasitic disease of human is malaria
Plasmodium spp
Kills 3,000,000 people each year
Transmitted by mosquito
Toxoplasma
Humans get from cats
Causes birth defects and mental retardation when pregnant mom exposed

13. Life Cycle of Plasmodium vivax

14. 19-2 Algae
Objectives
Compare and contrast the variety of plant-like protists
Explain the process of alteration of generations in algae

15. Diversity of Protists: Green Algae – The Chlorophyta
Phylum Chlorophyta
Approximately 7,500 species
Inhabit oceans, freshwater, snowbanks, tree bark, and turtles backs
Many are symbionts with fungi, plants, or animals
unicellular, multicellular
Morphology
cell wall that contains cellulose
Possess chlorophylls a and b, and
Store excess food as starch

16. Green Algae: Chlamydomonas
A minute (<25 μ m), actively moving flagellate
Inhabits still, freshwater pools
Fossil ancestors date back over a billion years
Anatomy:
Definite cell wall
Single, large, cup-shaped chloroplast
Many with a bright red eyespot, or stigma on chloroplast
Two long, whip-like flagella

17. Electron Micrograph of Chlamydomonas

18. Spirogyra

19. Multicellular Green Algae

20. Volvox

21. Red Algae – The Rhodophyta
Multicellular
About 5,000 species
Live mostly in warmer seawater, some as deep as 200 m
Economic Importance
Agar - capsules; dental impressions; cosmetics; culture medium; electrophoresis; food prep.
Carrageen - an emulsifying agent used in chocolate, low-fat foods, & cosmetics
The reddish-black wrappings around sushi rolls consist of processed Porphyra blades

22. Red Algae

23. Brown Algae – The Phaeophyta
About 1,500 species
Most live in colder ocean waters along rocky coasts
No unicellular or colonial brown forms
Morphology:
simple filaments
large multicellular forms that may exceed 200 m in length
Pigments:
Chlorophylls a and c
carotinoid pigment gives them their color

24. Brown Algae

25. The Phaeophyta
Multicellular forms of green, red, and brown algae are called seaweeds
Laminaria (a kelp), and Fucus, (rockweed), are common intertidal seaweeds
Nereocystis and Macrocystis often form forest-like thickets in deeper waters
Sargassum forms floating masses where other organisms find shelter
Harvested for food and fertilizer
Macrocystis is source of algin, a thickener for foods

26. Yellow-green Algae – The Chrysophyta
Diatoms (formerly Bacillariophyta) are the most numerous unicellular algae in the oceans
Significant portion of phytoplankton
Cell wall
Contains silica
Diatomaceous earth used as
Filtering agents
Sound-proofing materials
Polishing abrasives

27. Dinoflagellates – The Pyrrophyta
About 4,000 species of unicellular aquatic and marine organisms
Morphology:
Cell walls
Typically with two flagella
Symbiotic with corals
Some lack chloroplasts and are parasitic
Gymnodinium brevis may cause “red tide”
Produce a powerful neurotoxin that has caused massive fish kills
Consume shellfish during outbreak can cause respiratory paralysis

28. Diatoms and Dinoflagellates

29. Fish Kill and Dinoflagellate Bloom

30. The Euglenoids – Phylum Euglenophyta
Small freshwater unicellular organisms
Lack cell wall
Have two flagella and an eyespot
Have Chloroplasts so are photosynthetic
If light is not available can ingest food

31. Euglena

32. Algae go through an alternation of generations
Alternate between haploid (gametophyte)and diploid (sporophyte) body forms

33. 19-3 Slime Modes, Water modes, and Dewy mildews
Objectives
Contrast the cellular differences and life cycles of the two types of slime molds
Discuss the economic importance of downy mildews and water molds

34. Diversity of Protists: Slime Molds
Plasmodial Slime Molds - Phylum Myxomycota
Body in the form of a plasmodium
Diploid, multinucleated, cytoplasmic mass
Enveloped by a slimy sheath
Eventually produces sporangium which in turn produces spores
Cellular Slime Mold - Phylum Acrasiomycota
Body in the form of individual amoeboid cells
Later aggregate into pseudoplasmodium which then forms sporangium & spores

35. Plasmodial Slime Molds

36. Diversity of Protists: Water Molds - Phylum Oomycota
Most live in the water
Body filamentous, appearing like true Fungi
Cell walls largely of cellulose rather than chitin
The organism is diploid
Phytophthora infestans caused the 1840’s potato famine in Ireland
Saprolegnia is often seen as a white, cotton-like coating on dead aquarium fish

37. Water Mold

38. Ancient green algae ancestor to plants
Origin of Protists
Some protists share characteristics of plants, animals, and fungus
Shared common ancestor
Ancient green algae ancestor to plants