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All photosynthetic?
Most are photosynthetic but of course there are exceptions
Some are not photosynthetic and are actually parasites of other seaweeds!
The role of seaweeds
• Transform solar every to chemical energy in the form of organic matter– Energy is then available for consumption
• Habitat• Oxygen producers
Structure of seaweeds
• Seaweeds are eukaryotic
• Seaweeds still lack the specialized structures and reproductive mechanisms characteristic of terrestrial plants
• Wide range of variation among seaweeds
Variation
• Rocky shore- small and sturdy to withstand waves– Some delicate ones live on other seaweeds
• Kelps- found offshore in cold waters (giants)
General Structure
• Seaweeds lack true leaves, stems, and roots of plants.
• Thallus- Complete body• Blades- Leaf-like flattened portions of the thallus, large
surface area, photosynthesis• Pneumatocysts- Gas-filled bladders that can keep
blades close to sea surface• Stipe- Stem-like structure for support, blades originate • Holdfast- Attaches the thallus to the bottom and well
developed in kelps
Green Algae
• Most are freshwater and terrestrial• 10% of the 7,000 species are marine• Most have a simple thallus compared to the
other 2 groups• Thought that land plants evolved from green
algae– Pigments and food reserve are the same
Types of green seaweeds
• Filamentous types may be branched or unbranched • Enteromorpha- thin thallus in the form of a hollow
tube• Ulva- Sea lettuce is paper thin• Valonia- forms large spheres or curious spherical
clusters.• Caulerpa- Single giant cell with many nuclei• Codium- Deadman’s fingers• Halimeda- Calcareous green algae (coral reefs)
Brown Algae
• Coloration – varies from olive green to dark brown– Fucoxanthin over chlorophyll
• Almost all of the 1500 species are marine• Often the dominant primary producers on
temperate and polar rocky coasts.• Largest and structurally most complex (Include
the kelps)
Types of Brown Algae
• Ectocarpus- Finely filamentous thallus • Dictyota – thallus is flat and branched• Padina- Fan-shaped and lightly calcified• Desmaretia- branched
• Some are exposed at low tides at the middle and upper levels of rocky shores
• Gas-filled floats – rockweeds or wracks
Sargassum
• Brown algae found in warm waters (Gulfs of Mexico and California)
• Sargasso weed has spherical air bladders to keep small leaf like blades afloat
• Most grow on rocks• Offshore in huge masses• Sargasso Sea– Area in Atlantic
Sargassum Sea
• http://www.youtube.com/watch?v=JFxhlyJ3U4Q
Kelps
• Most complex and largest of all brown algae• Great importance – provide food and shelter for many
organisms. • Laminaria- species of kelp where a single large blade can be
up to 10 ft• Agarum and Alaria – Rib runs along the middle of a single
blade• Egregia- Feather boa kelp• Eisenia- Southern sea palm• Nereocystis- Bull kelp• Pelagophycus- Antler like branches
Brown Algaes
• kelp.gifkelp.gif
Ectocarpus
Dictyota
Padina
Desmarestia
Laninaria
Agarum
Alaria
Egregia
Nereocystis
PelagophycusEisnia
Macrocystis
• Largest of kelps• Massive holdfast attaches to the bottom• At the base of each blade a gas-filled
pneumatocyst• Can grow 20 in per day in optimal conditions• Form kelp beds or forests– Among the richest, most productive environments
in the marine world
Kelp Forest
• http://www.youtube.com/watch?v=GcbU4bfkDA4
• What coast of North America can they be found?
• What do kelps consist of?• What do young kelp compete for?• What do fish use the kelp forest for?• Why does the canopy make a good nursery
environment?
Red Algae
• More red algae that green and brown combined
• Red pigments known as phycobilins• Essentially marine– Of the 4000 species, only a few are fresh water or
soil• Live in most shallow-water marine
environments
Structure of Reds
• Simplified in structure by becoming parasites of other seaweeds
• A few have lost all chlorophyll and are heterotophs
• Most are filamentous – Thickness, width, arrangement of filaments varies
Types of Reds
• Gelidium • Gracilaria• Endocladia – wirey clumps on rocky shores from Alaska
to S. Ca.• Gigartina- Most massive of the red algae• Porphyra-Common on rocky shores above the lowest
tide mark• Rhodymenia –Common in North Atlantic• Chondrus –Irish moss and can tolerate wide ranges in
temp, light and salinity
Coralline Algae (Corallina)
• Red algae that deposit calcium carbonate in their cell walls
• Important in several marine environments • Calcified thallus takes a variety of shapes• Color varies from light to intense reddish-pink• Warm-water coralline algae are actively
involved in formation and development of coral reefs
Bingo• Thallus• Blades• Pneumatocysts• Stipe• Holdfast • Green algae• Red algae• Brown algae• Enteromorpha• Ulva• Valonia• Caulerpa• Halimeda• Gigartina• Chondrus
• Fucoxanthin• Ectocarpus• Dictyota• Padina• Desmarestia• Rockweeds• Sargasso Sea• Laminaria• Nereocystis• Pelagophycus• Macrocystis• Kelp forest• Phycobilins• Coralline algae• Gracilaria• Porphyra