Microscopic animals can be found in water, soil, food, and on our bodies. To observe them, a microscope or powerful hand-held loupe is needed. Unpolluted freshwater ponds and hay infusions are good sources for observing microscopic animals. Protozoa, rotifers, daphnia, and tardigrades are among the many types that can be found. Soil and mosses also contain many microscopic animals. Samples should be stored in an area with plenty of daylight and oxygenated daily. Microscopes with different magnifications can be used to observe them.
Microscopic animals are fascinating in their variety and are found all around us: in water, soil, food and on our bodies. Observing microscopic animals involves knowing where to look for them and some sort of magnification to make them clearly visible. A microscope is usually needed, although in some cases a powerful hand-held loupe can reveal a lot.
One of the best places to look for microscopic animals is in an unpolluted freshwater pond. By taking samples from different parts of the pond, the whole variety of microscopic inhabitants can be visualized. Microorganisms need a food source, so rather than open water, the best places to look are at the bottom of the pond among gravel, mud and debris such as decaying leaves and among vegetation such as aquatic plants and algae. It’s a good idea to take samples from both sunny and shady areas. A jar or glass attached to a long stick is useful for reaching awkward places.
A very convenient way to observe microscopic animals at home or in the laboratory is to make an infusion of hay. A suitable container, such as a jam jar, is filled with pond water, then a small amount of hay or dry grass is added. It is left to rest in a location with a reasonable amount of daylight, and a variety of microorganisms will appear in the following days and weeks. These can be observed by taking small samples of the water using a pipette and viewing the sample through a microscope. Samples from different places – near the surface, at the bottom and around the rotting hay – will reveal different organisms.
Among the many types of microscopic organisms that can be found in pond water or hay infusions are protozoa, rotifers, daphnia and tardigrades, also known as water bears. Protozoa are unicellular organisms that usually swim freely; strictly speaking, they are not classified as true animals, but they are capable of moving independently and are often considered so. Rotifers, although mostly similar in size to protozoa, are multicellular animals and have a clearly visible internal structure. Tardigrades are found in almost any environment where water is present, even if only intermittently, and have four pairs of legs. Daphnia, or water fleas, are relatively complex aquatic organisms with visible internal organs, compound eyes, and a circulatory system.
Other good sources of microscopic animals are soil and mosses. These contain many protozoa and rotifers, as well as nematodes, tardigrades and small arthropods such as mites, which, although barely visible to the naked eye, require magnification to see in detail. Even dried-up puddles and other seemingly unlikely places can harbor interesting microscopic life. Many microorganisms can enter a dormant state to survive inhospitable conditions and will become active again when circumstances are more favourable. Often, adding water – rainwater rather than tap water – to a dry sample and leaving it for a few days will result in a multitude of microscopic animals being seen.
Pond water samples and hay infusions should ideally be stored in an area with plenty of daylight and oxygenated daily by bubbling air with a pipette. If you need to top up the water, use rain water or pond water. Tap water normally contains traces of chlorine, which can be harmful to microorganisms.
For microscopic viewing, take a small sample with a pipette and place a drop on a microscope slide. Place a coverslip over it by lowering it at an angle to avoid trapping air bubbles. Microscopes will have three or four objective lenses giving different magnifications, such as 30, 100, 200 and 400 times. It’s best to start at the lowest magnification, then zoom in on areas of interest.
Larger microscopic animals, such as mites, are best viewed at lower magnifications. Protozoa and rotifers can be seen in detail at 100-200x magnification. Since most of these microorganisms are transparent, internal details can best be seen by adjusting the microscope’s aperture to maximize contrast.
Protect your devices with Threat Protection by NordVPN
