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microscope Diatoms

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Photos and info courtesy of Maurice Vaughan


Diatoms are a major group of algae, and are among the most common types of photoplankton.  They can be found in the oceans, in freshwater, in soils and on damp surfaces, but as most are just a few microns in size, you can't see them with the naked eye.  The photos below show their intricate structures magnified 200 and 400 times through a microscope.




A Marine Diatom (name unknown)
Freshwater Diatoms Surirella Ovalis (left) and Cocconies (right)
A Marine Diatom (name unknown)
A Freshwater Diatom named Cymbella
A Freshwater Diatom named Pinnularia Viridis
A Freshwater Diatom (name unknown)

Diatom cells are contained within a unique silica cell wall comprising two separate valves or (shells).  The cell walls are also called "frustules" and their two valves overlap one another like the two halves of a petri dish.


Photographing Diatoms


Before they can be photographed the diatoms need to be filtered and cleaned.  They are then placed inside a drop of liquid on to a cover slip and heated until the cover slip is dry.  Then can then be mounted on to a normal microscope slide using a high refractive mountant (Storax) and left to settle for two days.

The slide can then be mounted on a normal compound microscope using the X20 or X40 objectives and a X10 eye piece.  The camera used for the photos above was a Minolta D2 which has the capability of X2 magnification.  The camera needs to be mounted to the microscope using an adaptor, and then the photos can be taken through the trinocular head of the microscope.

Once the photos are taken they can be cropped and colour added using photo editing software.  The blue texture seems to show the structure of the diatoms up well.  The large brownish diatoms shown above are marine diatoms the blue diatoms are freshwater diatoms.