Multicellular Primary Producers

Seaweeds and GrassCh. 6

Structure• Thallus:

– Complete body• Blades:

– Leaf-like portions• Pneumatocyst:

– Gas-filled bladders– What’s the importance of

these?• Stipe

– Stemlike structure, support• Holdfast:

– Attaches the thallus to the bottom

Types of Seaweed: Green Algae• 10% of the 7,000 species

of green algae are marine• It is thought that land

plants evolved from green algae– Similar pigments and food

reserve

• Common on rocky shores and tidepools

Galapagos Iguana

Iguanas, Green Algae, and Sea Lions?

Brown AlgaeDead Man’s Fingers Rockweed

•Color varies from olive to dark green•There are yellow-brown pigments, in addition to chlorophyll•Often exposed on low tides

More Brown Alage: The Kelps

Bull Kelp• Nereocystis• Up to 100 ft long• Large pneumatocyst at upper end

– Filled with mixture of gasses, including CO2

Giant Kelp• Macrocystis• Largest kelp—up to 330

ft!• Can grow 20 inches in

one day!

Giant Kelp

Life in the Kelp Forest

Red Algae• More species of red

algae than green and brown combined

• Shallow water, marine environments

• Chlorophyll masked by red pigment (phycobilins)

• Coralline algae shown with gooseneck barnacles

Economic Importance of Kelp and Other Seaweeds

• You tell me . . .