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