Diatoms capture solar energy and produce a quarter of our planet's oxygen. Despite their tough, siliceous shells, these phytoplankton are abundant food for copepods and are at the base of the marine food chain.
Diatoms are single-celled organisms with nuclei and chloroplasts. They are protists living individually or forming chains, zig zags or spirals. The first diatoms – the centrics - appeared in the Jurassic age some 200 million years ago, as combinations of yeast-like organisms and algae. Over the eons,diatoms acquired new genes, shapes and complex metabolisms. They've become champions of photosynthesis, while retaining many properties of animal cells.
With other photosynthetic protists, they produce oxygen and absorb CO2. Over millions of years, diatom shells have sunk to the seabed, forming thick layers of silica and fossil fuels.
65 million years ago, diatoms survived the mass extinction of dinosaurs. They adapted to polar regions, where they still proliferate. Pennate diatoms appeared later and colonized new ecological niches. Some can glide over surfaces and congregate into a very thin layer called a biofilm. Pennates produce special metabolites and toxins that can ravage aquafarms.
When the sun shines, if iron and silica abound, diatoms flourish by dividing into smaller and smaller units. Survival demands that size be restored. Miniature diatoms transform into male and female gametes that join together and give birth to children much bigger than their parents.
Proliferation of diatoms at the poles result into explosive blooms visible from outerspace.