1. Kingdom Protista Developed by Adam F Sprague & Dave Werner
Multicellular Algae
Kingdom Protista
Developed by Adam F Sprague
& Dave Werner

2. Characteristics of Algae:
Plantlike members of the kingdom Protista
Eukaryotes
Most unicellular, but some multicellular
Autotrophic – contain chlorophyll & make food by photosynthesis
Planktonic
Produce oxygen
microscopic to seaweeds hundreds of feet in length
Do not have true roots, stems, nor leaves
Form gametes (eggs & sperm) in single-celled gametangia (chambers) instead of multicellular gametangia like true plants
Found in freshwater, marine, and moist soil habitats
Most have flagella at some time in life cycle
Algae cells contain organelles called pyrenoids organelles that make & store starch

3. Structure of Algal Cells:
The body of algae is called the thallus 
Algae may  be unicellular, colonial, filamentous, or multicellular
Unicellular algae are single-celled & make up phytoplankton (a population of photosynthetic organisms that begins many aquatic food chains)
Phytoplankton make much world's carbohydrates & are the major producers of oxygen

4. Structure of Seaweeds
Filamentous algae have slender, rod-shaped thallus arranged in rows joined end-to-end
Holdfasts are specialized structures in some filamentous algae that attaches the algae so it can grow toward sunlight at the surface

5. Structure of Seaweeds:
Multicellular algae often have a large, complex leaf-like thallus & may have stem-like sections and air bladders called pneumatocysts
 Macrocystis is among the largest multicellular algae

6. Structure of algae vs. seagrass

7. Filamentous algae Enteromorpha

8. Multicellular algae Macrocystis

9. Classification:
Algae are classified into 3 phyla, based on color, type of chlorophyll, form of food-storage substance, and cell wall composition
All phyla contain chlorophyll a
Many species of algae reproduce sexually and asexually
Sexual reproduction in algae is often triggered by environmental stress

10. Chlorophyta (green Algae): 7000 species
May be unicellular, multicellular, or colonial
Include Spirogyra, Ulva, & Chlamydomonas
Contain chlorophyll a & chlorophyll b and carotenoids (orange & yellow pigments) as accessory pigments
Store food as starch
Cell = cellulose, some add CaCO3
Habitat -freshwater, moist surfaces, or marine environments
Some have whip-like flagella for movement
May live symbiotically as lichens
Thought to have given rise to terrestrial plants

12. Phaeophyta (brown algae): 1500 species
Contain chlorophyll a & chlorophyll c and fucoxanthin (brown pigment) as accessory pigments
Most multicellular- growing in cooler marine habitats
Includes kelps & seaweeds
Largest protists
Specialized rootlike holdfasts
Specialized air bladders
Stemlike structures are called the stipe
Store food as a carbohydrate called laminarin
Include Laminaria & Fucus

14. Rhodophyta (red algae): 4000 species
Multicellular algae that mainly grow deep in warm marine waters
Some freshwater species exist
Highly branched thallus
Contain chlorophyll a & phycobilins (red pigments) to trap sunlight
Store food as starch
Cell walls contain cellulose and agar (used as a base in culture dishes to grow microbes)
Some species contain carageenan in their cell walls used for gelatin capsules & in some cheeses

16. Common Marine algae of Barnegat Bay

17. Enteromorpha

18. Ulva lactuca (Sea Lettuce)

19. Agardhiella

20. Fucus (rockweed)

21. spongomorpha

22. Sargassum
A closeup of a small mass of sargassum weed. The numerous small round spheres are floats filled with carbon dioxide. These provide buoyancy to the algae.

23. There are numerous types of marine algae found throughout our back bay areas, this has just been a sample of what you will find.

24. Diatom Reproduction fig. 5.6
Asexual = Cell Division into Auxospores
Produces Blooms
Sexual = Egg & Sperm

25. Reproduction in Unicellular Algae Bio book p.528
Asexual Phase
Algae absorbs its flagellum
Haploid algal cell then divides mitotically from 2 to 3 times
From 4 - 8  haploid flagellated cells called zoospores develop in this parent cell
Zoospores break out of the parent cell & eventually grow to full size

26. Sexual Phase
Haploid cells dividing mitotically to produce either “plus” or “minus” gametes
A plus gamete and a minus gamete come into contact with one another, shed their cell walls, and fuse to form a diploid zygote
This resting stage of a zygote is called a zygospore & can withstand bad environmental conditions
When conditions are bad, the thick wall opens and the living zoospore emerges

27. Chlamydomonas

28. Reproduction in Multicellular Algae:
Oedogonium is a multicellular, filamentous green algae with specialized cells called gametangia that form gametes
The male gametangia or antheridium makes sperm, & the female gametangia or oogonium makes eggs
Sperm are released into the water & swim to the egg to fertilize them
The fertilized egg or zygote is released from the oogonium & forms thick-walled zoospores
Zoospores undergo meiosis so one cell attaches to the bottom & develops a holdfast while the other zoospores divide & form a filament

30. Spirogyra, another filamentous green algae, reproduces by conjugation

31. Two filaments align side by side, their adjacent cell walls dissolve, & a conjugation tube forms between them Fertilization occurs when a + gamete cell moves through the tube & fuses to the - gamete cell  Zygote forms a thick walled spore (sporangium) that breaks away from the parent & forms a new filament Conjugation Tube between Spirogyra

32. Ulva fig.6.11
The leaflike algae Ulva has a sexual reproductive cycle characterized by a pattern called alternation of generations
 Alternation of generations has two distinct multicellular phases- a haploid, gamete-producing phase called a gametophyte and a diploid, spore-producing phase called a sporophyte
Alternation of Generation also occurs in more complex land plants, but the gametophyte & sporophyte do not resemble each other