Microbes are
SUPER SMALL!
Some can
multiply and mutate
IN MINUTES!
And they're
EVERYWHERE!

Microbes are singled-celled organisms that are invisible to the eye. But some can be seen with microscopes. They're the oldest form of life on Earth.

Microbes are all over the surfaces of your house, on your skin, and in the air you breathe. Right now, trillions of microbes are living in your body! Don't worry, while some are "germs," most microbes are harmless to humans.

Find out more about three types of microbes: bacteria, viruses, and protists.

photo bacillus bacteria
Bacillus

Bacterias

  • Still counting: 4,000 species have been identified, but there are probably millions more.
  • Spirals, squiggles, and more: Bacteria come in lots of shapes, including balls, rods, commas, spirals, and cubes.
  • On the go: Some swim forward by beating a tail-like structure called a flagellum; others slide on the slimy secretions they ooze.
  • Our microbes, ourselves: About 100 trillion bacteria live in and on a human body. They work so closely with human cells that we depend on each other for survival. They're like another organ!
photo influenza virus
influenza

Viruses

  • Masters of mutation: Some viruses have the power to change quickly to survive in different environments.
  • Micro-pirate alert: Viruses can never live on their own. They invade other cells for survival and to create more viruses.
  • Achoo! Many different viruses can cause the common cold, but rhinoviruses are the most common.
photo Acanthamoeba protist
Acanthamoeba

Protists

  • What are they?!?! Protists are single-celled organisms that have a nucleus and organelles, like the cells in our bodies.
  • Mostly harmless: About 40,000 species of protists are known — only a few cause disease in people.
  • Big in a little world: Protists are the largest microbes, and they can be seen under a simple microscope.
  • Super swimmers: Most protists live in moist habitats, from droplets of water in the soil to the ocean.