Algae

1. Algae By Erica Gonzales

2. What are algae? • Protists that use photosynthesis • Classified by their pigments: • Purple, • Rusty-red, • Olive-brown, • Yellow, • Golden Brown • Both unicellular and multicellular

3. Characteristics Unicellular Algae Multicellular Algae • Phytoplankton • Major producer of nutrients and oxygen in the world • Classified into 3 phyla: • Euglenoids • Diatoms • Dinoflagellates • Look like plants • No roots, stem or leaves • Large and Green

4. Unicellular Algae Euglenoids Diatoms Dinoflagellates

5. Euglenoids • Unicellular aquatic protists • Plant AND animal characteristics • Made of cellulose; no cell wall • Have flagella to move towards light or food • Have a flexible pellicle around cell membrane

6. Parts of a Euglenoid Notice that there are similarities between the Euglenoid and a plant cell

7. Characteristics Plant-Like Animal-Like • Contain chlorophyll • Conduct photosynthesis • Autotrophic • Can eat food when light is not available • Ingest food like protozoa • Heterotrophic

8. Diatoms • Unicellular photosynthetic organisms • Have shells composed of silica • Abundant in fresh and saltwater ecosystems • Box-shaped • Contain chlorophyll and carotenoids (a pigment) for golden color

9. Diatom Shells Each species of diatoms has its own unique shape, differently patterned with grooves and pores.

10. Food • Use sunlight for food (photosynthesis) • Food is stored as oils, not starch • Gives them an oily taste to fish that eat them • Oil allows them to float near water’s surface for sunlight

11. Reproduction Asexually Sexually • Two halves of the box split • Each pieces produces a bottom half to fit inside it • Half of offspring are smaller than parents • Stops when diatoms are ¼ original size • Then switches to sexual reproduction • Produce gametes (egg or sperm) • Fuse to form zygotes • Zygote fully develops and divides asexually for a while

12. Diatom Reproduction

13. Death • Shells sink to ocean floor at death • Million-year-old diatom deposits have been found • Used for tooth or metal polishes

14. Dinoflagellates • Have cell walls made of thick cellulose plates • Contain chlorophyll, carotenoids & red pigments • 2 flagella in grooves right angles to each other • Live in freshwater, but mostly saltwater • Can live symbiotically with jellyfish, mollusks and coral • Some species emit light

15. Toxic Dinoflagellates • Several species produce toxins • One species Pfiesteria piscicida can cause massive fish kills • Gonyaulax catanella produces extremely lethal nerve toxins • A very numerous population of these cause a red tide • Inhabited by 40 to 60 million dinoflagellates per liter of seawater • Can make humans ill

16. Red Tides The yellow and orange spots in the water are red tides, areas so densely infested by toxic dino-flagellates.

17. Multicellular Algae Red Algae Brown Algae Green Algae

18. Red Algae • Multicellular marine seaweeds • Thallus – body of a seaweed: lacks roots, stem and leaves • Uses structure called holdfasts to attach to rocks • Found in tropical waters or in cold waters on rocky coastlines

19. Pigments • Contain Chlorophyll and phycobilins – photosynthetic pigments that absorb green, violet, and blue light (the only lights that penetrate water past 100 meters) • Allows algae to deeper than most seaweeds

20. Brown Algae • Live in salt water along rocky coasts in cooler areas • Contain chlorophyll and fucoxanthin • Fucoxanthin – yellowish-brown carotenoid (a pigment) that gives them their brown color • Most species have air bladders • Keep them floating near the surface for sunlight

21. Kelp • Largest and most complex brown algae • Thallus (body) is divided into holdfast, stripe and blade • Holdfasts anchor them to rocks or ocean floor • May grow to 60 meters long • Some giant kelps form underwater forests • Many organisms live in them

22. Green Algae • Most diverse algae; over 7000 species • Have many pigments that give yellow-green color • Main one is chlorophyll • Live in: freshwater, saltwater, moist soil, tree trunks, even the fur of sloths

23. Colonies Multicellular Unicellular DifferentTypes of Green Algae Colony: group of cells that lives together in close association

24. Volvox Colony • Composed of hundreds of cells with flagella in one layer to form a hollow ball • Cells are connected by strands of cytoplasm • Flagella face outwards and beat in unison to spin the colony in the water • Smaller balls, “daughter colonies” form inside the hollow space • Wall of larger colony eventually breaks to release the daughter colonies

25. Reproduction • Reproduce sexually AND asexually • Fragmentation – (asexual reproduction) an individual breaks up into pieces and each piece grows into a new individual • Some species use this method of asexual reproduction • Alternate from producing sexually and asexually throughout lifecycle • Produce gametes for sexual reproduction • Produce spores for asexual reproduction

26. Alternation of Generations • Pattern of alternating between existing as a haploid and diploid organism, creating 2 different generations • Gametophyte – haploid form of organism; produces gametes • They fuse to form a zygote • Sporophyte – diploid form of organism, also zygote of previous generation; produces spores • Cells undergo meiosis and eventually become haploid spores that can become gametophyte

27. Life Cycle of Green Algae Throughout their lives, green algae switch from being a diploid to a haploid.