diatoms eukaryotic algae common type of phytoplankton unicellular or colonies primary producers in...
Post on 20-Dec-2015
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Diatoms
• 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
• Diatom cells are contained within a unique silica cell wall called frustules, comprising two separate shells – two shells overlap one other like
the two halves of a petri dish
•Silica is made in the cell and then extruded to the cell exterior and added to the wall.
Reproduction
• When a diatom divides to produce two daughter cells, each cell keeps one of the two halves and grows a smaller half within it.
• After each division cycle the average size of diatom cells in the population gets smaller.
• When a certain minimum size is reached, they reverse this decline by expanding in size to give rise to a much larger cell – Caused by sexual reproduction.
Ecology
• 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.
Nanotechnology
• The deposition of silica by diatoms may also prove to be of utility to nanotechnology
• Diatom cells manufacture different shapes and sizes, potentially allowing diatoms to manufacture micro- or nano-scale structures which may be of use in a range of devices, including drug delivery