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 Phytoplankton
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. Different Types of Green Algae
Colonies
Multicellular
Unicellular
Different Types 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.