1. Algae (Chapter 20)
Aquatic plants

2. Ecological Role Habitat
marine or fresh water, possibly in very moist soil, tree trunks, snow and on rocks
They have to live in moisture due to the lack of internal transport tubes called “vascular tissue” to transport water and nutrients
chlorophyll containing organisms, with no true roots or leaves

3. Ecological Role Chlamydomonas nivalis
phenomenon commonly known as watermelon snow, red snow or blood snow

4. Ecological Role Major roles as phytoplankton (unicellular forms)
number one food producers (act as a food source for many organisms)
supply 70%+ of global oxygen supply
as seaweed (multicellular forms)
provide food source and habitat for marine organisms
source of agar, among other things

5. Taxonomy 3 main phyla (green, brown and red algae)
algal classification is very unstable, some biologists are not convinced that all algae are plants and prefer algae to be placed in Kingdom Protista, with only some multicellular phyla (seaweed) remaining as plants, so there is a bit of confusion with classification to the present day

6. Taxonomy Phylum chlorophyta (Green Algae)
marine and freshwater habitats
contain chlorophylls a and b
store food in form of starch
reproduction is quite complex! Undergo alteration of generations, which means they shift back and forth between haploid(n)and diploid (2n) generations
asexual reproduction involves haploid sporophytes
sexual reproduction involves gametes

7. Taxonomy Phylum chlorophyta (Green Algae)
have evolved into many forms such as :
a) Single-celled Green Algae (e.g. Chlamydomonas)
grows in ponds, ditches and wet soil
small, egg-shaped cell with two flagella
light sensitive eyespot that can sense bright light or darkness
large, cup-shaped chloroplast that photosynthesizes to produce starches
two contractile vacuoles
no cellulose in cell wall
characteristics of both Protists and Plants

8. a) Single-celled Green Algae (e.g. Chlamydomonas)

9. Taxonomy Phylum chlorophyta (Green Algae)
have evolved into many forms such as :
b) Colonial Green Algae (e.g. Volvox)
many identical cells living together
each cell functions independently
colonies can have anywhere from 500 to 50,000 cells
individual cells are connected by strands of cytoplasm that allow them to communicate when colony needs to swim
a few cells are specialized for reproduction
saytoplsm

10. b) Colonial Green Algae (e.g. Volvox)

11. Taxonomy Phylum chlorophyta(Green Algae)
have evolved into many forms such as :
c) Threadlike Green Algae (e.g.Spyrogyra and Oedogonium)
create long, threadlike colonies called filaments
grow and reproduce asexually
if filaments are broken, the cells continue to divide and grow
can reproduce sexually by gamete production
attach to the bottom of a lake or pond by a specialized holdfast cell
Spirogyra has spiral-shaped chloroplasts!!
filament

12. Spyrogyra

13. Oedogonium

14. Taxonomy Phylum chlorophyta (Green Algae)
have evolved into many forms such as :
d) Multicellular Green Algae (e.g. Ulva or ‘sea lettuce’)
live in marine environments
are only 2 cells thick, so easy diffusion of gases
holdfasts attach Ulva to rocks
A holdfast is a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, 

15. Taxonomy Phylum Rhodophyta (red Algae)
almost exclusively marine habitats
red because of the presence of pigment phycoetrythrin, an accessory pigment that reflects redlight and absorbs blue light
contains chlorophyll only
since blue light penetrates water to a greater depth than light of longer wavelengths, these algae can live a somewhat greater depths than other algae, up to 170 m.
rhodophytes are important sources of food, such as nori (Poryphyra) and dulse (Palmaria)- an Icelandic snack!
also used as fertilizers on coastal agricultural land
some rhodophytes are important in the formation of coral reef.
rhodofaites

16. dulse (Palmaria)- Nori Poryphyra
Nongeniculate corallines are of particular significance in the ecology of coral reefs, where they provide calcareous material to the structure of the reef, help cement the reef together, and are important sources of primary production.

18. Taxonomy Phylum Phaeophyta(brown Algae)
mostly marine habitats
brown colour results from the dominance of the xanthophyll pigment
contains chlorophyll a and c
brown algae generally larger and more species found in colder waters than other seaweeds
common forms include kelps (Sargassum) and wracks (Fucus)
chlorofil

19. Taxonomy Phylum Phaeophyta (brown Algae)
Kelp forest Sargassum
wracks (Fucus)

20. Taxonomy Phylum Phaeophyta(brown Algae)
also some forms use for food such as Japanese kombu (Laminaria japonica)
kelps grow in underwater forests, some grow to more than 60 m. long and are secured to rocks with holdfasts structures
Fucus keep upright with help of air bladders
chlorofil

21. Reproduction
Quick review: Meiosis vs. Mitosis
chlorofil

22. Reproduction
chlorofil

23. Reproduction in Ulva
chlorofil

24. Reproduction in Fucus
Alteration of generation = alters between gametophyte (n) and sporophyte (2n)
Female gamete = egg (n) is large and cannot swim
Male gamete=sperm(n) is small and swims with help of flagella
Diploid sporophyte plant (large seaweed structure) is the only multicellular part of the life cycle
chlorofil

25. conceptacles
receptacles

26. Reproduction in Fucus
The blades (leaves) of the sporophyte plant contain specialized reproductive structures (receptacles, in openings called conceptacles), one produces eggs (oogonia) and one produces sperm (antheridia)
The eggs and sperm are released into the water and if sperm find some of the floating eggs, fertilization occurs and a zygote(2n) is formed
The zygote sinks to the ocean bottom and, with luck attaches to an object such as a rock where the zygote will grow by mitotic division into a new diploid (2n) sporophyte
riceptical