There are approximately 2,700 different kinds of earthworms. Worms live where there is food, moisture, oxygen and a favorable temperature. If they don't have these things, they go somewhere else. In one acre of land, there can be more than a million earthworms. The largest earthworm ever found was in South Africa and measured 22 feet from its nose to the tip of its tail.
Worms tunnel deeply in the soil and bring subsoil closer to the surface mixing it with the topsoil.
Slime, a secretion of earthworms, contains nitrogen. Nitrogen is an important nutrient for plants. The sticky slime helps to hold clusters of soil particles together in formations called aggregates. Charles Darwin spent 39 years studying earthworms more than 100 years ago. Worms are cold-blooded animals.