Diatoms, microscopic algae that encase themselves in ornate, exquisitely patterned glass shells, are found in prolific numbers in every ocean on earth. They have fascinated scientists for centuries –in fact, ever since the microscope was first invented and men could sketch their beauty. Justifiably, the diatom is called the jewel of the sea.
Alfred Nobel, inventor of dynamite in the 1860’s, used silica from diatoms to stabilize nitroglycerin, which enabled him to form portable sticks of the explosive. Fossilized diatom shells are used commercially in many ways today –for example, to illuminate road paint, purify wine, and filter swimming pool water.
Far more important, though, is the fact that these tiny one-celled plants account for one fourth of the photosynthesis on our planet. Researchers Allen Milligan and Francois Morel, of Princeton University, U.S.A., have found that silica in the diatom’s glass shell causes chemical changes in the water inside it, creating an ideal environment for photosynthesis. The reason the glass is so ornate, scientists believe, is that a greater surface area is thus exposed to the water inside the cell, making photosynthesis more efficient. Just how these minute but beautiful cases are formed from silicon dissolved in seawater is still a mystery, but what researchers do know is that by absorbing carbon dioxide and releasing oxygen, diatoms play a vital role in sustaining life on earth, perhaps an even more important role than most land plants.
Morel rates diatoms among the most successful organisms on earth. Milligan adds that without their appetite for carbon dioxide, “the greenhouse effect might be much more severe.”
When diatoms die, their carbon remains sink to the ocean floor and eventually fossilize. Some scientists believe that in this form, under intense pressure, diatoms have contributed to the world’s oil reserves. Concern is growing, however, that as seawater temperatures rise because of global warming, this allows bacteria to eat the diatoms’ remains before they can sink, and carbon is released back into the surface water. Thus, even this tiny “jewel of the sea” is part of a marvelously designed life-sustaining system that could now be under threat.