Bacillariophyceae

1. BIO 14 YA
June 29, 2013

2. • Eukaryotic algae
• Common type of
phytoplankton
• Unicellular or colonies
• Primary producers in the
food chain
• Over 200 genera of living
diatoms, and approximately
100,000 species
• Found in freshwater and
marine environments

3. • Made up of silica
• Called “Frustule”
• Pillbox or petri-dish in
shape
• Epitheca vs Epivalve
• Hypotheca vs Hypovalve
• Mid junction = girdle

4. • Do not tend to have a
strong, highly visible
color
• In groups, yellowish –
golden in color
• In larger groups, deep
brown or black

5. • Very diverse in size
• Can form colonies
and filaments to two
feet!
• Two types of diatoms
based on shape:
•Centric
•Pennate

6. • Radial symmetry
• Primitive
• Raphe Absent
• Almost immoblie
• Large vacuole with
many discoid
cloroplasts

7. • Bilateral symmetry
• Boat-shaped
• Raphe/pseudoraph
e is present
• Few elongated
chloroplasts
• advanced

8. • Strands of mucilage
are secreted
through the raphe
• Strands attach cells
to substrate
• Cells glide over the
substrate

10. • Cell division
• Daughter cells
receiving the
hypovalve are
smaller
• Daughter cells
receiving the
epivalve are the
same with the
parent

12. • Planktonic
• All centric and some pennate
• Benthic
• Pennates, these secrete mucilage to
form biofilm
• Meroplanktonic
• Temporary, during periods of
turbulence they are carried out in the
open water

13. • Diatoms produce an estimated 20% to
25% photosynthesis on the planet
• A major food resource for marine and
freshwater microorganisms and animal
larvae
• A major source of atmospheric
oxygen

14. • Richest source of
diatom fossils are
deposits of their
skeletons known as
diatomite or
diatomaceous earth
• Mined for
cleansers, paints, filte
ring agents, abrasives
and toothpastes

15. http://www.nanowerk.com/news/newsid=1591.
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