Methods
Plankton net
Organisms called plankton have a great variation in the size, and it is the forms from 20-500 my (1my=1/1000mm), which can be collected with a plankton-net. This plankton is often called the net-plankton. Cells lesser than 20 my i diameter is called nano-plankton. The nanoplankton will pass through the finest mesh used i nets. Nanoplankton is collected when water sample can sediment for a rather long time and the bottom sediments then studied in the microscope. The net is towed through the water, vertically or horizontally and the organisms are held back and show up in the glass while the water pass on.
Click and look at the video-clip of net collecting.
The sample has to be stored in a cold place until the microscopic work can start. If you not are able to study the plankton the same day or the next day, the samples have to be preserved. This can be done with iod-vinegar solution (lugol), or with formalin to which a little iodine can be added. For beginners we recommend studies of still living plankton, which give quite a different experience of colours and locomotion than studying preserved material.