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Different types of microbes caught on film with the aid of differential interference contrast, phase contrast and bright field microscopy. Most of what you see in these photographs can be found in any garden pond or small body of freshwater. A low power stereomicroscope is a useful aid for sorting out the catch and isolating whatever organism you think may make a good photograph.
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Fig 1.This is a photograph of the very large heliozoan called Actinospherium, which can grow up to 1mm in diameter, however, I have to confess that I never seen a specimen as large as this. This protozoan was photographed with a X40 DIC objective. Note the large frothy vacuoles and also the axopodia that radiate out from the cell body in order to snare passing microbes. It is usual to see numerous food vacuoles in this creature during the spring.This animal will lurk for ages between the weeds in the open water waiting for its next victim. It is difficult to know how much this animal ingests over any period of time in the wild. Any experiments that are carried out with the animal in a home laboratory are fraught with difficulties, and I have always found this particular animal very hard to keep in a viable condition. It seems to be very prevalent during the spring and autumn but can vary from week to week in its numbers.
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Fig 2. This photograph was taken with a X25 Leica DIC objective on a Leica Orthoplan microscope using the Orthomat camera. Amoebas always look good when viewed under the DIC microscope. Loads of detail can be seen within the cell body. Finding a large Amoeba such as the amoeba proteus can be very hard and may take months of searching. I usually come across such a beast about two or three times per year and it is always by accident. However, if you know a little about the biology of such organisms, then at least you can plan on where the best place to search for your quarry might be.
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Fig 3. This beautiful but very small green alga is called Dictyosphaerium and is quite common in most dredges that I make with plankton net. The individual cells are about 10um in diameter and are all held together with a set of very fine connecting tubes. This photograph was taken with a phase X40 objective.
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Fig 4. Again this microbe is part of the plankton and is very common in the ponds found in Epping Forest. Dinobryon is a member of the Chrysophyceae and consists of single cells that live within a small vase like protective shell called a lorica. They swim with the aid of two flagella one being longer than the other but easily seen under the microscope. It is easily identified in the field by looking very much like a short tree branch.
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Fig 5. This very strange microbe goes by the name of Sphaerastrum fockie and is a member of the actinopoda. The diameter is in the region of about 30-35mm not including the axopodia. This microbe is quite common in the reed beds that are found in Wake valley pond. This microbe does not do too well in captivity and must be photographed as soon as possible. X40 DIC objective.
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Fig 6. Micrasterias. This desmid is without doubt one of the most beautiful Desmids to photograph, whether with Darkfield, phase, DIC or bright field. The background has been manipulated with the use of Photoshop. This alga is a member of the Zygnematales and can be very varied in its appearance. Thanks to Wim Van Egmond for the material.
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Fig 7. This photograph was taken with phase contrast on a Zeiss photomicroscope 111. Desmids can be found almost in any fresh water habitat, but the best places to search are in bogs and other acidic waters where they may be abundant. This type of microbe is also a very fine object to photograph with a DIC objective. Because of its very flat body it is easy to get everything into focus. The nucleus is in the centre of the desmid also noting the newly emerged semi cell on the right.
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Fig 8. Phacus is a Euglenoid and is usually found in conjunction with its more famous cousin Euglena. This single celled alga is very flat and oval in shape and has a large round transparent opening in the centre. There is a flagellum but unfortunately it cannot be seen on this photograph. The very faint red object is called the stigma or eyespot. The smaller colourless round objects are plastids. This photo was taken in brightfield with a X40 planapo objective. The spines at the posterior end of the organism are a good indicator of which species the alga is.
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These two contrasting photographs
show the very beautiful Euglena, which can change the shape of
its pellicle with extraordinary ease. The Euglenoid consists of
a pellicle that can propel the organism forward by what is known,
as metaboly, which is very similar to peristaltic motion seen
within the stomach or intestine of metazoans. This type of movement
is used over areas where there is little water or between detritus
at the bottom of the lake or pond. The pellicle is mostly protein
with some lipid. When swimming through the water the Euglena uses
its long flagella (which can be seen at the light microscope level)
undulating back and forwards. These flagella emanate from the
reservoir at the anterior of the cell body. Close by the stigma
or red eyespot can be seen as a red clump of cells, these help
the organism to move to light or dark areas if and when the need
arises. Much research as been carried out on this organism with
over 800 species recorded so far.
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These two photographs shows the abundance of fresh water microbes that can magically increase in numbers within a matter of 30- 60 minutes under the microscope slide. The beauty of this spirochete and the rod shaped bacteria is that they appear to be quiescent for long periods and if caught at the right moment good photographs are easy to come by. I can watch these microbes for ages with out tiring they are fascinating to watch when actually moving. I have noticed that sometimes for no apparent reason large numbers of certain bacteria will congregate in certain areas sometimes in long lines while others will bunch for what appears to be for no reason. Obviously there is some attractant there, which I cannot see with the microscope, it could possibly be chemicals, which they can detect with their receptors. These microbes come up well with either phase contrast or DIC and are always worth keeping an eye open for.
These images were captured with the aid of a Carl Zeiss photomicroscope 111 and a Leitz Orthoplan microscope with various lenses and condensers. Steve and Eleanor Durr collected most of the organisms from the ponds at Epping Forest. The photographs were taken on 64 tungsten slide film and then scanned onto the hard drive of my computer.
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This large lake at Holkham in Norfolk was pea green with various cyanobacteria. Apparently this occurs each year at about the same time and clears up after about one month. Aphanizomenon was found in great numbers and could be seen with the naked eye. The colonies of Aphanizomenon look like clumps of freshly cut grass. |
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