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Microscopic Organisms Found in Pond Water

Pond water harbors many interesting organisms that you can see under a microscope. In fact, sampling pond water and viewing it under a microscope can be one of the most rewarding ways to learn about microorganisms because of the diversity and activity of the life found there. Pond water can be skimmed from the top, sampled from near the bottom or collected by holding a water plant over the sampling container and letting the water drain in. All of these methods will collect different types of organisms because of the differences in these environments.

Water Bears
- Water bears are tiny animals with eight legs, and some species of water bear live on plants in fresh water or in the sediments at the bottom of ponds. Water bears use their sharp mouths to suck out juices from algae, or to eat nematodes and rotifers. They walk along slowly through the water and are between 0.1 mm and 1.5 mm in size.
Crustaceans
- Microscopic crustaceans feed on decaying matter and on other live microscopic organisms. They have an exoskeleton which they must shed occasionally to grow. A crustacean can be as small as 0.1 mm or can be as big as a full grown shrimp or crab. However, not all crustaceans look like the crabs you are familiar with. Some simply look like small transparent beans with legs, and some look like microscopic fleas.
Bacteria
- Bacteria are usually only visible as dots or strands of dots under a microscope, because they are so small. Bacteria play a vital role in the pond water by consuming waste from other organisms and converting some harmful compounds, like ammonia, to useful materials for other life, like nitrates which algae use as food.
Worms and Larvae
- Some of the worms that you find in pond water will be visible to the naked eye. However, some will be incredibly tiny but behave in much the same way that the visible worms behave. Don't be confused by some of the creatures that look and behave like worms, which are actually insect larvae. They can be differentiated by their small proto-legs and distinct heads.
Rotifers
- Rotifers are interesting little animals that are transparent and are known for wheel-like appendages covered with little hairs called cilia. They are multicellular and range in size from 40 micrometers to over 2 millimeters. Rotifers are found in almost every water environment, but because most of them are so small they can be difficult to see.

Nature