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Figure 1. The water flea or Daphnia is a member of the crustacea and are found in most fresh water ponds; in fact they can be found in their thousands in just one container full of water. Daphnia can be anything from about 1mm to 3mm in length. Their movement consists of a series of jumps, which are produced by the antennae. The whole body is enclosed within a carapace. Daphnia will eat algae, which can sometimes be seen in the gut of the crustacean. Low power bright field. |
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| These two photographs show the very beautiful placoderm desmid Closterium which is fairly common around my part of the world. The cell wall as a very granular texture and is divided in the mid region by what is called the isthmus. There are something in the region of between 200/300 species on mainland Britain. The nucleus can be seen in the middle of the isthmus in the DIC photograph on the right. Note also the large pyrenoids in each semi cell. Both photographs are X400. |
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| These four photographs show the beautiful alga Eudorina elegans. This alga is very common and can occur in thousands in just a very small sample of pond water. Eudorina is a member of the Chlorophytes and is a colonial alga with anything from 16-32 biflagellate cells. The red eyespot of the individual cells can vary in size across the sphere and therefore gives some polarity to the colony. All the cells within the colony can divide and form daughter colonies. There is sexual reproduction in this species, which involves separate male and female colonies of different sizes, the female being the larger of the two.The lower two photographs were taken with differential interference contrast objectives and show the cell nucleus and stigma. |
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| This spherical ball of cells called Uroglena is a very common component of the plankton of certain lakes and ponds. Uroglena can be mistaken for Volvox by the inexperienced observer. The individual cell is shaped like a pear and each cell has two flagella of unequal length and also a stigma both of which are not seen in the above photographs.. Uroglena belongs to the Chrysophyta or golden algae. The cause of the golden brown coloration is due to the pigment fucoxanthin. There is possibly something in the region of a thousand species of the Chrysophyta worlwide with over one hundred being located in the British Isles. |
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This photograph shows the Desmid called Closterium that is very common in eutrophic waters. There are numerous species with many having a small vacuole at the apex of the cell, which hold small crystals that display the phenomena of Brownian motion extremely well. |
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| The above three images were taken with a nikon coolpix 4500. |