1. CLASSIFICATION OF LOWER ORGANISMS

2. Remember:  There are 6 Kingdoms for all organisms  Animalia, Plantae, Fungi, Protista, Eubacteria, Archaebacteria  “Lower organisms” are generally the Eubacteria, Archaebacteria, Protista and Fungi

3. Definitions  Phylum: the taxon containing closely related classes  Phylogeny: The evolutionary history of a group of organisms that share a common ancestor

4. Protists - Introduction  Single celled eukaryotes  Appeared approximately 1.5 billion years ago  115 000 species, all very diverse in cell structures, patterns of nutrition, reproduction and habitats  Their phylogeny is very complex and difficult to classify  To simplify in this class, protists have been broken down/classified based on their nutritional pattern: animal-like, fungus-like and plant-like

5. Animal-Like Protists  Also called Protozoans  All are heterotrophs - they eat and ingest material from their surroundings  Are 4 phyla of protozoa, classified by their type of locomotion  Numerous in types of species and population numbers, similar to bacteria

6. Animal –Like Protists: Zooflagellates  Phylum Mastigophora  Possess 1 or more flagella to help them move  Feed on other protists or are internal parasites on animals  Reproduced asexually via longitudinal fission  Example: Trypanosoma gambiensis causes sleeping sickness that destroys RBCs, other tissues and one’s nervous system until the person loses consciousness

7. Animal-Like Protists: Amoebas  Phylum Sarcodina  Most are free-living forms  No set body shape  Psuedopods (projections of cytoplasm) enable them to move and feed through endocytosis (engulfing organisms with their pseudopods)  Some are parasitic Example: Entamoeba causes amoebic dysentery, found in the water in tropical regions

8. Animal –Like Protists: Ciliates  Phylum Ciliophora  Covered with hairlike projections called cilia  Rigid outer covering called pellicle maintains their shape (amoebas don’t have this)  All ciliates are aquatic heterotrophs  Paramecium is an example

9. Paramecium Digestion  Beating of its cilia sweeps food into oral groove  Membrane pinches off, surrounds food and a food vacuole is formed  Food vacuole joins up with a lysosome which breaks down the food with digestive enzymes  Usable products are absorbed in cytoplasm, undigested food is removed via anal pore

10. Paramecium & Structure  Have 2 types of nuclei – large macronucleus and smaller micronucleus  Reproduction by binary fission (asexual)  Micronucleus (ei) divide by mitosis and macronucelus simply pinches apart to produce two daughter macronucleus  Paramecium also use sexual reproduction via conjugation

11. Animal-Like Protists: Sporozoans  Phylum Sporozoa  Produce spores during asexual reproduction  Sporozoa are non-motile and parasitic; get nutrients from bodies of hosts  Best known sporozoan is genus Plasmodium that causes malaria

13. Fungus-Like Protists  Also called....SLIME MOULDS!!!!  All are heterotrophic and most are decomposers that feed on dead plants and animals by endocytosis  Live in cool, damp habitats

14. Fungus-Like Protists: Acellular Slime Moulds  Single celled  Most of life is a wall-less mass of cytoplasm with many nuclei  Cytoplasm moves using pseudopodia (network of strands)  Reproduce using spores; spores scatter and germinate

15. Fungus-Like Protists: Cellular Slime Mould  Live in fresh water, damp soil or decaying matter  Move like amoebalike cells  When food scarce, they form a large multicellular mass and eventually release spores

16. Fungus-Like Protists: Water Moulds  Most live in water; some on land  May have seen growing on dead fish as whitish cottony substance  Most land species decompose dead matter which is good, but few are parasitic to plants  Irish Potato famine in mid 1800s caused by Phytophthora infestans

17. Plant-Like Protists  Are 24 000 species of protists that contain chlorophyll and carry out photosynthesis, and so they resemble plants  We look at Euglenoids and Algae

18. Plant –Like Protists: Euglenoids  Are unicellular flagellates and many members of this group photosynthesize to produce food  Species called Euglena gets fed in 2 ways  In sunlight it is autotrophic (photosynthesis)  In dark feed as heterotroph on dead organic material in water

19. Plant –Like Protists: Algae  Resemble plants because they have chloroplasts that have chlorophyll  Some are single-celled, some live in colonies, some are multicellular  Are 6 main groups of algae; we discuss 3 here

20. Algae: Diatoms  Have golden colour due to yellow-brown pigments in their shells  Outer covering is made of two halves  Each species has a characteristic shape  Abundant in ocean; also classified as phytoplankton

21. Algae: Dinoflagellates  Are single-celled algae, have 2 flagella  Most are photosynthetic  Abundant in marine environments  Each species has a specific shape  Tend to be luminescent: when surrounding water is agitated, they give off light!!  Reproduce by mitosis

22. Interesting to Know....  Rapid population growth called an algal bloom  When dinoflagellate Gonyaulax polyhedron blooms it’s called a red tide

23. Algae: Green algae  Can be single celled or colonial  Each cell has 2 flagella that move the cell around  Ancient green algae are thought to have given rise to the first plants because they have cellulose in their cell walls and their chloroplasts are similar to those of plants  Multicellular algae known as seaweeds

24. Algae: Green algae Colony of Algae (Volvex) Giant Kelp (multicellular Algae) can grow to 100 m and has the fastest growth rate of any organism.