Diatoms: unique eukaryotic extremophiles providing insights into planetary change

The diatoms (Division Bacillariophyta) are aquatic, pigmented single-celled photosynthetic eukaryotes. They are a major component of the food chain in marine, estuarine and freshwater ecosystems. These diploid organisms have the ability to take dissolved silica out of the water column, and use it to create their cell walls. The taxonomy and classification system for the group is based to a large part on cell wall symmetry, as well as the number, type, position and organization of the many perforations in the glass. As a group, diatoms are found in almost every water type of water body around the globe, including a wide range of extreme environments. Individual species, however, have limited distributions and ecological requirements. Preservation of the glass cell walls in sedimentary basins has left nearly a 120 million year record. Species-related distributions, and well-preserved record make diatoms an excellent tool for environmental reconstruction and monitoring. New research on diatoms includes applications to conservation biology, astrobiology, nanotechnology, and biofuels.