An earthworm has five pairs of hearts and is both male and female. Several hundred million years old, earthworms are among the earth s most ancient inhabitants. There are thousands of species of earthworms in the world. The nightcrawler is the largest type of North American earthworm and, therefore, prized by anglers. Common garden or field worms look somewhat like nightcrawlers but are smaller.
Earthworms come in many other colors from pink, tan, and brown to blue, green, and purple.
Most earthworms species aren t native to the United States. Many species were introduced from Europe, their cocoons probably packed into soil under the shoes of colonists horses. They re more prevalent in the humid sections of the eastern United States than they are in the arid West. A very healthy 16X16 inch section of backyard contains about 100 earthworms. Some worms live 60 years or more, but most live less than a year.