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