Caption: Marine pennate diatom frustule (Navicula sp.). The Navicula genus of diatoms comprises more than 10,000 species. The body or frustule is composed of two halves which fit tightly together. The cell walls contain silica dioxide (glass) which are preserved in deposits known as diatomaceous earth. Once hardened into rock it is called diatomite and can be used for many purposes including filters, fillers and abrasives. Diatoms represent about 25% of the plant biomass in the world. Found both in fresh water and salt water these microscopic unicellular plants are important biomass and oxygen producers. Through their photosynthesis, greenhouse gasses are converted to organic material and they therefore play a decisive role in the global carbon dioxide circulation. When individual cells die they remain as siliceous (silica dioxide) cell walls and sink to the bottom of the lake or ocean. Research has shown that the walls of fossil diatoms can give valuable information about past environment and climate conditions and serve as indicators for historical dating of sediments. Industries use the diatom silica walls in the form of diatomaceous earth for polishing material and for filtering wine and beer. In the field of nanotechnology the motility of such tiny cells and the silica cell wall design has been used as a pattern for car wheels. Omega-3 fatty acids of the diatoms have been found to benefit the nervous system. There are many phytoplankton diatom genera that are an important part of the food chain.
Magnification*: x700
Type: SEM
Copyright 2009 Dennis Kunkel Microscopy, Inc.
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