Project: Make your own Plankton Net
Project: Make your own Plankton NetPlankton are very common in all bodies of water, but they are often very spread out and it would be hard to look at them without making a "plankton concentrate". A net is the tool that is most often used to increase the number of plankton within a volume. The resulting sample is then looked at with a microscope (but you can use a magnifying glass or just your eyes).
A "professional" plankton net is made up of a very expensive nylon mesh with highly accurate hole sizes in it, but you don't need to be so complicated. As long as a mesh can filter the critters out of the water, the net will accomplish its purpose. I will give you instructions on how to construct a simple plankton net of your own out of common household items.
Net Assembly
Cut one of the legs off of the nylons near the top. Unwind the coat hanger (be careful - you might need some help with this), then create a ring about 15-25 cm (6-10 inches) in diameter (it can't be much larger than the top of the cut stocking leg). You can twist the ends of the hanger together with the pliers and shape the wire into a circle as best as you are able. Put the top end of the leg through the wire ring and fold it back over the outside of the wire ring. Staple or tape the nylon leg to attach it to the wire ring. Cut a small hole in the toe end of the nylons about the same size as the bottle mouth opening you have. Stretch the end over the mouth of the bottle or jar. Wrap the rubber band tightly around the nylons to secure it to the bottle.
You now need to make a pyramid of string in front of the net so the net will tow with the mouth of the net facing forward and not collapse. To do this, you need to tie three evenly spaced strings, each about 60 cm (2 feet) long to the coat hanger ring at the top of the net. Tie the other end of these strings to a washer or another small ring (in a pinch you can use a tie-tape, but it will be harder to attach your towing rope to it) which will be in front of the net when you tow it.
Plankton Collection
All you have to do now is attach a longer towing string or rope to the ring and tow it from a boat (go really slowly and don't get it near the propeller), a dock, toss it (or drag it while wading) into a pond or lake and pull it back a couple of times. The longer you tow, the more you will catch.
To get at your sample, remove the rubber band and dump your bottle into a tray (with dark color if you want to see your plankton) or larger bottle to store the sample. You may see little dots swimming around, or possibly just drifting. Plankton will not keep for long, so don't wait too long before looking at it (refrigeration will help to keep it fresher, but not much longer than a day or two). You can also preserve your plankton by mixing your water half-and-half with rubbing alcohol (ask someone responsible before using this - it is a dangerous chemical). Unfortunately, most plankton are extremely small so you might not get much detail using just your eyes (but many zooplankton are about 1 mm long so you can see them if you look carefully for them swimming). Your school might have a microscope. Ask a teacher if you would be able to use it to view your samples. If you can't get use a microscope, try putting your sample into a large thick glass jar and tilt the jar around a little. The curvature of the glass will cause some magnification of the things near the edge (check some of your jars at home to find a good "magnifier" candidate and keep it out of the recycling). It's not great, but it just might be enough to help you to see something.
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