Algae

1
Algae
2
Algae

• diverse
• simple
• mostly aquatic
• mostly photosynthetic
• Belong to the kingdom Protista
• Eukaryotic
• So they have a nucleus and membrane bound
  organelles

3

• Photosynthesis takes place in chloroplasts
• They can be either
• Green
• Brown
• Red

4
How are they different from plants?

• No flowers
• Simple reproductive structures
• Lack leaves, roots, and stems

5
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

6
Diatom Reproduction
Frustules get smaller and smaller.
Why do diatoms get extremely small during periods
of high reproduction called blooms?

• Usually asexual reproduction

7
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

8
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

9
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

10
Special Dinoflagellates

• Some are bioluminescent
• Some release toxic substances during large blooms

11
Pfiesteria

• Phantom dinoflagellate
• Parasite that feast on fish
• Cause open sores in fish
• Temporary memory loss in humans

12
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 islands famous pink beaches.
13
Radiolarians

• Spherical
• Shells of silica
• Pseudopodia to eat

14
Ciliates

• Many hair like extensions called cilia to move
• Very common as freshwater Paramecium

15
Multicellular Algae

• Seaweed
• Sometimes called macrophytes or macroalgae
• Also eukaryotic
• Can range from small to large
• Kelp often form large forests underwater

16
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

17

• Some seaweed have a support called a stipe where
  blades originate
• Holdfast holds thallus to ground

18
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

19
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

20
Seagrasses

• Not algae
• Actually adapted land plants that live in water
• Roots grow sideways under sediment
• Provide homes to many organisms

21

• Castro, Peter and Huber, Michael E. Marine
  Biology. New York McGraw-Hill, 2007.