The tiny paramecium hardly looks like our idea of an animal. It has no eyes, no ears, no heart, and no brain. Yet despite its size and shape, this one-celled organism can do almost all the things that any animal can do.
A paramecium takes in food through a hole on one side of its body, digests it, and eliminates waste through another opening. It can move through water by waving hairs on its sides, and reacts to very warm or salty water by scurrying away from it.
These creatures sometimes reproduce by exchanging bits of matter from one organism to another, and defend themselves by shooting out tiny spike-like hairs all over their body to form a sort of “armor” against attackers.
So, although you have millions of cells in your body, and the paramecium has just one, you both behave.the same in many ways, and both belong to the group of living things we call the animal kingdom!