Archaea

1

• Archaea
• Resemble bacteria superficially but may be more
  closely related to eukaryotes than bacteria
• May be heterotrophs or autotrophs
• Methanogens
• Nitrogen fixers
• Important decomposers
• Abundant in sediments
• Extremophiles
• Sulfur rich hot springs
• Acid/Alkaline lakes (acidophiles)
• Hydrothermal vents (thermophiles)
• Deep sea (barophiles)
• Antarctic (psychrophiles)

2

• Unicellular Algae
• Eukaryotes
• Photosynthesis in chloroplasts
• Lack flowers, stems, leaves, roots
• Diatoms (Bacillariophyta)
• Unicellular
• May form chains
• Cell enclosed by silica (SiO2) frustules (test)
• Test usually perforated and ornamented with
  spines or ribs (Why?)
• Perforations allow gases, nutrients, waste
  products to pass through test to cell
• Important open-water primary producers,
  especially in temperate and polar regions

Fig. 4.8b
Fig. 15.3a
3
Fig. 5.5
4

• Unicellular Algae
• Diatoms (Bacillariophyta)
• Reproduction
• Asexual - Cell division
• Sexual - Egg Sperm --gt Auxospore

Fig. 5.6
5

• Unicellular Algae
• Diatoms (Bacillariophyta)
• Reproduction
• Explosive population growth --gt Bloom
• May deplete nutrients locally
• Sediments beneath areas where diatoms are
  abundant may contain many tests
• Diatomaceous oozes
• Diatomaceous earth

6

• Unicellular Algae
• Dinoflagellates (Dinoflagellata/Pyrrophyta)
• Possess two flagella
• Motile
• Covered with theca made of cellulose plates
• Theca may have spines

Fig. 5.7a
7

• Unicellular Algae
• Dinoflagellates (Dinoflagellata/Pyrrophyta)
• Possess two flagella
• Motile
• Covered with theca made of cellulose plates
• Theca may have spines
• Important open-water primary producers,
  especially in tropical regions
• Trophically diverse
• Autotrophic
• Heterotrophic
• Mixotrophic
• May bloom like diatoms
• Red tides
• Brown tides

8
http//www.whoi.edu/redtide/
9

• Unicellular Algae
• Dinoflagellates (Dinoflagellata/Pyrrophyta)
• Some forms live symbiotically with corals,
  anemones, jellyfish, giant clams, sponges
• Zooxanthellae
• Lose flagella
• Especially important in reef building corals
• Some forms can be extremely toxic
• Pfiesteria
• - Blooms triggered by coastal pollution
• - Toxin can cause memory loss in humans

10

• Unicellular Algae
• Other Algae
• Silicoflagellates (Chrysophyta)
• Silica test, usually with spines
• Single flagellum
• Coccolithophorids (Haptophyta)
• Covered by calcium carbonate coccoliths
• Coccoliths may be important components of
  sediments
• Cryptomonads (Cryptophyta)
• Lack skeleton
• Two flagella

Fig. 5.8
Fig. 5.9
11

• Protozoa
• Foraminiferans
• Test (shell) made of calcium carbonate (CaCO3) or
  agglutinated sediment particles
• Fossil tests used to age geological deposits
• May have multiple chambers
• Tests increase in size as organism grows
• Feed by extending pseudopodia through pores in
  test
• Trap bacteria and other small organisms/detritus
• Pelagic forms (calcareous)
• Often have spines
• Tests may form foraminiferan oozes, esp. in
  shallow water beneath tropics (white cliffs of
  Dover England)
• Benthic forms (calcareous or agglutinated)
• Calcareous tests can be important sources of sand
  for beaches

12
(No Transcript)
13
http//earthguide.ucsd.edu/earthguide/imagelibrary
/orbulinauniversa.html
http//www.ucl.ac.uk/GeolSci/micropal/foram.html
14

• Protozoa
• Radiolarians
• Test made of silica (SiO2)
• Tests may form radiolarian oozes, esp. in deep
  water in temperate and polar regions
• Feed by extending pseudopodia through pores in
  test
• Trap diatoms and other small organisms/detritus
  (Why diatoms?)
• Ciliates (Ciliophora)
• Use cilia
• Locomotion
• Feeding
• Free living
• Pelagic (Tintinnids)
• - Lorica
• Benthic
• Parasitic

15
http//rmbr.nus.edu.sg/research/terrestrial/fungi.
htm

• Fungi
• Unicellular or multicellular
• Mostly microscopic
• Heterotrophic
• Important decomposers
• Especially in mangrove forests
• Some disease causing forms
• Host to algae in lichens

16

• Multicellular Algae - Seaweeds
• Macroalgae
• Complex but lack specialized structures of true
  plants
• General Structure
• Body thallus
• Flattened portion blade
• Not true leaves
• No veins
• Upper and lower surfaces identical
• No tissues for transport of water, nutrients
  minerals
• Increase surface area (Why?)
• Main sites of photosynthesis
• Float pneumatocyst
• Anchor holdfast
• Do not penetrate sediment or absorb water
  nutrients

17
Fig. 6.1