Diatoms

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Marine Primary Producers
Primary Producers Notes
Primary Producers - make organic matter from
CO2 - usually by photosynthesis.
Until the 20th Century there were only
“plants” and “animals”.
50’s and 60’s questions about fungi, protists,
bacteria arise?
By 70’s five kingdom classification “hand”
diagram, now six.
phytoplankton in food chain
Kingdom Monera - prokarotyes - cells that
lack organelles
ex. Bacteria - 250,000 on head of pin on
average, under optimal conditions they can
reproduce by cell division twice an hour.
Exponential grow
Bacteria perform all basic chemical
processes found in other organisms (probably first life forms on planet). Fossil
bacteria 3.8 bil
Decay Bacteria - heterotrophic important
in cycling nutrients. decomposer
Autotrophic Bacteria - photosynthetic
or chemosynthetic (like bacteria at
hydrothermal vent communities).
Cyanobacteria (blue/green algae) chlorophyll but no chloroplasts.
May have been first photosynthetic organism
on the planet and maybe responsible for our
atmosphere. Also carries out nitrogen fixation.
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Diatoms -
Kingdom Protista
Division - “Plants”.
Phylum - animals.
Diatoms belong to the division Chrysophyta.
Phylum- Bacillariophyta
Are part of phytoplankton.
Diatoms account for majority of food and O2 production in
coastal waters.
• 12,000 species - half are marine.
• Single celled, eukaryotic (has nucleus) autotrophic.
• Chlorophyll a photosynthetic pigment in chloroplasts.
• Pill box of glass.
• Frustule (cell wall) of
pectin and silica.
• Chloroplasts scattered
throughout
cytoplasm.
• Elongated - bilaterally
symmetrical =
pennate or wheel
shaped - radially
symmetrical = centric.
Reproduce by simple cell division (mitosis). Asexual,
genetically identical daughter cells.
Some pennate species can move under their own power
(cytoplasmic slime produces gliding movement).
Build up of dead diatoms = diatomaceous
earth; used in pool filters, mild abrasive for
toothpaste.
White Cliffs of Dover
Adaptations to keep near the surface/defense against
zooplankton:
Light build, oil droplets, same density as H2O,
long thin hairs, threads or horns
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