Algae • diverse • simple • mostly aquatic • mostly photosynthetic • Belong to the kingdom Protista • Eukaryotic • So they have a nucleus and membrane bound organelles
Photosynthesis takes place in chloroplasts • They can be either • Green • Brown • Red
How are they different from plants? • No flowers • Simple reproductive structures • Lack leaves, roots, and stems
Diatoms • Unicellular organisms that are usually planktonic • Cell walls made of glass-like Silica • The glassy shell is called a frustule • Has two halves and resembles a box
Diatom Reproduction Frustules get smaller and smaller. Usually asexual reproduction Why do diatoms get extremely small during periods of high reproduction called blooms?
Ooze • When diatoms die, their glassy shells sink to the bottom of the ocean creatingdiatomaceous ooze • Does that sound familiar? • Mined and used in things like • Swimming pool filters • Toothpaste • Temperature and sound insulators
Dinoflagellates • Two flagella • one wrapped around a groove along the middle of the cell • One trailing behind it • Cell wall made of plates of cellulose
Zooxanthellae • Special dinoflagellate that lives in close association with coral and other animals • In coral, they photosynthesize and the coral uses the nutrients released by them
Special Dinoflagellates • Some are bioluminescent • Some release toxic substances during large blooms
Pfiesteria • Phantom dinoflagellate • Parasite that feast on fish • Cause open sores in fish • Temporary memory loss in humans
Protozoans (animal like protists) • Foraminiferans • Shell made of calcium carbonate • Pseudopodia to trap diatoms to eat Homotrema rubrum is a foram that is bright red and lives on corals. Very common in Bermuda; skeletons made the island’s famous pink beaches.
Radiolarians • Spherical • Shells of silica • Pseudopodia to eat
Ciliates • Many hair like extensions called cilia to move • Very common as freshwater Paramecium
Multicellular Algae • Seaweed • Sometimes called macrophytes or macroalgae • Also eukaryotic • Can range from small to large • Kelp often form large forests underwater
Structure • Lack true leaves, stems, and roots • Entire body is called the thallus • Leaf-like flattened portions are called blades • Pneumatocysts are gas filled chambers that keep blades close to surface to maximize photosynthesis
Some seaweed have a support called a stipe where blades originate • Holdfast holds thallus to ground
Types of seaweed • Green algae • Most live in freshwater • Brown algae • Largest, most complex seaweeds • Kelp • Red algae • More marine red than brown and green combined
Economic Importance • Mariculture: farming of seaweed is big in China, Japan, and Korea • Phycocolloids are gellatins used in many foods • Algin used to stabilize foods • And much more…
Seagrasses • Not algae • Actually adapted land plants that live in water • Roots grow sideways under sediment • Provide homes to many organisms
Castro, Peter and Huber, Michael E. Marine Biology. New York: McGraw-Hill, 2007.