Earthworms (Lumbricus terrestris) are soft-bodied, segmented worms that belong to the Annelida phylum. Earthworms are also called nightcrawlers because they burrow down in the ground during the day and come above ground at night to feed.
Earthworms are invertebrates, meaning they don't have backbones. Most earthworms appear pink, brown or red in color.
While most earthworm species grow to be only a few inches long, some earthworms grow to a snake-like 22 feet. The longest earthworms live in Australia and South Africa.
An earthworm has a small brain, a digestive system, a reproductive system and a circulatory system with five pairs of hearts. Earthworms breathe through their skin instead of with lungs.
Earthworms are hermaphrodites, meaning they possess both female and male reproductive systems. Mating earthworms lie together and pass sperm to one other.
Earthworms are terrestrial worms that like to live in moist soil and leaf litter. Earthworms don't live in regions with permafrost, deserts or permanent ice and snow.
There are about 2,700 earthworm species in the world.