Protozoa

Protozoa are tiny, animal-like microorganisms that are usually made of one cell and can move on their own.

• Where they live: Protozoa are common in pond water, wet soil, and other moist places. Some also live inside the bodies of animals (including humans).
• How they move: Different protozoa move in different ways:
  • Amoeba moves using temporary “false feet” called pseudopodia.
  • Paramecium moves using many tiny hair-like structures called cilia, which beat like little oars.
• How they get food: Many protozoa take in food from their surroundings, often by engulfing tiny particles (Amoeba does this) or by sweeping food into a mouth-like opening (Paramecium does this).
• Why they matter: Protozoa are part of food chains in water—small animals eat them, and they help keep ecosystems balanced.
• A useful nuance: “Animal-like” does not mean they are animals like insects or fish. Protozoa are single-celled, but they still carry out all life processes (movement, feeding, growth, reproduction) within that one cell.

Thinking of protozoa as “one-cell creatures that can move and feed” makes it easier to remember what sets them apart from many other microbes.