1. Seaweeds and Plants

2. The term seaweed refers to the large marine algae that grow almost exclusively in the shallow waters at the edge of the world's oceans. They provide home and food for many different sea animals, lend beauty to the underwater landscape, and are directly valuable to man as a food and industrial raw material.

3. Structure of Seaweeds (also called macropyhtes and macroalgae)
thallus – the complete body
blades- the leaf-like, flattened portions of the thallus
pneumatocysts- gas filled bladders which help keep the blades near the surface
Why would blades need to be near the surface?
stipe- stem-like structure providing support
holdfast- attaches the thallus to the bottom

5. Types of Seaweeds
Green
Brown
Red

6. Green Algae
Live in freshwater, terrestrial and marine environments – only a small percentage are marine
Typically bright green because chlorophyll is not masked by other pigments

7. Common Green Algae Ulva – also known as sea lettuce
Codium – dead man’s fingers
Halimedia – numerous segments with deposits of calcium carbonate – important in the formation of reefs
Enteromorpha – often found in polluted areas

8. Sea Lettuce
Dead Man’s fingers

9. Brown Algae
Almost all species are marine and the most complex of all seaweeds
Color varies from olive green to dark brown
The color is a result of more yellow–brown pigments(fucoxanthin) then chlorophyll

10. Common Brown Algae
Ectocarpus – simplest brown algae which is widely distributed

11. Dictyota –thallus is flat and branched
Both found in the tropics
Padina – fan- shaped and lightly calcified

12. Desmarestia – the dominant species in cold water – known as Witch’s Hair
Fucus – have gas filled floats commonly found on both the Atlantic and Pacific coasts – known as rockweeds

13. Sargassum – also have air bladders -found growing on rocks but also found floating in huge masses
Particularly common in the Gulf of Mexico and the Sargasso Sea

14. Kelps – the most complex and largest of all the browns
Kelps – the most complex and largest of all the browns. They occur in great abundance – found below the low tide level in temperate and subpolar latitudes, providing food and shelter.
Common Kelps
Laminaria – made up of a single large blade – harvested for food

15. Postelsia – grows where the waves crash – known as sea palm
Nereocystis – 100 ft long stipes – bull kelp

16. Macrocystis – the largest of all the kelps, can grow 20 inches a day and get 330 feet. Grow close together and form kelp beds (forests)

17. Red Algae More species of red algae then green and brown combined
Red pigments called phycobilins which hide the chlorophyll
Inhabit most shallow marine environments

18. Common Red Algae
Dense clumps are common on rocky shores exposed at low tides
Longer- flatter branches predominate in areas less exposed to air

19. Chondrus – called Irish moss – can tolerate wide ranges of temperature, salinity and light and it shape varies depending on the conditions

20. Rhodymenia- common in the North Atlantic – has the most common shape of the red algae’s

21. Coralline algae – red algae that deposit calcium carbonate - important for reef formation
Variety of shapes – thin discs, branches with many joints, smooth or rough encrusting growths on rocks
Common variety - Corallina

22. Life History Reproduction in seaweeds is by asexual and sexual means
Four basic types of reproduction

23. Most Common form
The sporophyte produces spores by meiosis. These spores develop into a gametophyte. Both the spores and the resulting gametophyte are haploid.
The mature gametophyte produces male or female gametes (or both) by mitosis. The fusion of male and female gametes produces a diploid zygote which develops into a new sporophyte.
This cycle is known as alternation of generations.

24. Carposporophyte Generation
Very similar to sporophyte, except has a third generation – a diploid carpospore which develops into a sporophyte
Still has alternation of generations

25. Easiest of all
Thallus produces haploid gametes by meiosis (both male and female) which fuse to form diploid zygote which develops into new thallus (brand new plant).

26. Last of four types
The thallus is haploid and produces haploid gametes.
Fertilization occurs and forms diploid zygote which undergoes meiosis forming haploid spores which develop into new thallus.

28. Economic Importance Uses: to make paint
as a thickener in making shampoos, shaving cream
to thicken printing paste to provide sharper images
to make rubber products
making paper
cosmetics
found in fertilizers
wound dressings in hospitals

29. Food Uses
Phycocolloids – useful because they form gels at low concentrations
Algin – used as a stabilizer and emulsifier (think dairy)
Carrageenan – used as emulsifier as well.

30. Flowering plants Seagrasses – truly marine, live below water
Salt-marsh plants – land plants tolerant of salt
both salt – marsh plants and mangroves live in estuaries and have only their roots below the water
Mangroves – trees or shrubs adapted to live along tropical and subtropical shores around the world

31. Seagrass Zostera – called eelgrass
Look like grass, but not really a grass
Stems called rhizomes
Roots and shoots grow from stems
Small flowers – Why don’t they need pretty and large flowers?
Very important for providing shelter and food

32. Salt – Marsh and Mangroves
Provide habitat and breeding ground, protection against erosion, and provide a natural water purification system.
Spartina – called cordgrass
Mangrove forest