The uniqueness of diatoms
Diatoms are unicellular microscopic algae. Their uniqueness lies in their cell walls (shells) that consists of silicon dioxide. The shells consist of one to three layers of very specific patterns of tiny nanopores. These shells are designed by nature to take up visible light efficiently to enable an efficient photosynthesis. They are also designed for efficient uptake of nutrients and maintenance of optimal water levels in the algal cell. The shells also protect the algae from harmful substances and UV light.
Important in the ecosystem
20-25% of the oxygen that we breathe comes from diatoms. Diatoms form the basis of the food web and are eaten by everything from microscopic ciliates to large whales. Fossils indicate that diatoms have existed for at least 200 million years. The number of diatom species is estimated to around 20 000 – 2 000 000. New species are continuously identified and described. Diatoms can be found everywhere where there is moisture and some available light: in the ocean, on the seabed, in lakes, in and on ice – even on cave walls!
Diatoms photosynthesize, but they are also able to uptake small organic molecules. Thus, they can survive in darkness without forming resting stages. Diatoms contain chlorophyll a and c and, in addition, different carotenoids such as fucoxanthin, which give them a brownish colour. They store energy in the form of oil (lipids) and a carbohydrate called chrysolaminarin.