No bigger than specks of dust, incredibly diatoms can be seen from satellites in space when their numbers explode each spring and turn the sea green.  ‘The planet would be a very different place without diatoms,’ says Eileen Cox, a researcher at the Natural History Museum, ‘There are so many of these single celled plants in the sea that they produce almost a third of all the oxygen on earth.  That’s more than the rainforests.’ They take in carbon dioxide and convert it to food in sunlight using a coloured pigment called chlorophyll (which makes all plants green) and give off oxygen as a waste gas.

 

They are not just vital to the health of the atmosphere, without these beautiful creatures there would be no fish, seals, dolphins or whales.  Diatoms lie at the bottom of the marine food chain, everything else in the sea either eats them directly, like krill, or eats something that eats diatoms.  Even we are dependent indirectly on the activities of diatoms.  Vitamins in our diet are critical to our own health, but few of us know that vitamins A and D in cod liver oil, can actually be traced back to the diatoms eaten by the small fish that was eaten by the cod.

 

Diatoms form the largest component of the phytoplankton, from the Greek phyto, meaning plant, and plankton, meaning wanderer.  Drifting in the ocean currents in the sunlit layers of the surface waters, over a 100,000 different species exist and all live in exquisitely beautiful and intricate glass houses.  The amazing shapes of the tiny plants are actually thin double outer shells made of silica, which is the same material as glass.  The shells are called frustules, and they fit together like two halves of a pill box.  Each species has its own pattern of perforated holes, through which the diatom cell inside can absorb minerals and exhaust waste.  The holes also make it easier for the diatoms to stay floating in the water near the surface by decreasing their weight.  Spine or projection are thought to slow their rate of sinking.