Rod-shaped bacteria, seen through a microscopeThe tiniest living things can be seen only by using powerful microscopes. This "micro-life" is more correctly known as micro-organisms or microbes. They include bacteria, protists and some types of fungi. They are each made of just one living “unit”, called a cell. Some micro-organisms cause diseases in animals. We call them germs.
Minute bacteria live everywhere in their countless billions. They are found in the air, soil, water—even inside our bodies. Many kinds are vital to life (we could not digest our food without them), but harmful bacteria, called germs, may cause disease. Some bacteria have frilly edges and and long tails, which help them swim along.
Bacteria are the commonest living things. There are typically about a billion bacteria in a gram of soil.
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