Multicellular Primary Producers: Seaweeds and Plants
Multicellular Algae: The Seaweeds
•Macrophytes or macroalgae
•Multicellular, eukaryotic organisms
•There are 3 types of seaweeds;
• green
• brown
• red algae
General Structure of Seaweeds
•Body of seaweed (thallus)
•Leaf-like portions (blades)
o photosynthesis
o Gas-filled bladders (pneumatocysts)
•Stem-like structure that provides support (stipe)
•Attaches the thallus to the bottom (holdfast)
Fig. 6.1
•Green Algae
Division Chlorophyta
o Freshwater
o Marine
o Terrestrial
o Bright green from
chlorophyll
Ulva or sea lettuce
Codium
Brown Algae
Division Phaeophyta
oYellow-brown
pigment, fucoxanthin
oTemperate/polar
oRocky coast
oLargest/complex
Fucus, rockweed
Kelp
• Largest of all brown algae
• Macrocystis
o Largest of the kelp
o Grow 20in a day
• Kelp beds are rich in life, most productive
Red Algae
Division Rhodophyta
• Highest number of
species
• Red pigments; phycobilins
• Parasite for other
seaweed
• Porphyra, rocky shores
Coralline alga
• calcium carbonate in their cell walls.
Life History
•Reproduction
• asexual and sexual
• alternation of haploid and diploid generation
Economic Importance
• Mariculture
• Thick suspensions or gels at low concentrations
(algin, carrageenan, and agar)
• Dairy products such as ice cream and cheese
• Frosting, Rx, shampoo, shaving cream, rubber
products, paints, and cosmetics.
Flowering Plants
• Seagrasses
• true marine species adapted to soft-bottom
coastal regions
• Members of the lily family evolved from
terrestrial plants