A Q& A with Rhonda Sherman, extension specialist at North Carolina State University, sometimes called the “worm queen”:
How do earthworms eat?
They do not have teeth. A liplike extension over the mouth helps direct food into the mouth, where the muscular pharynx (throat) grabs it, coats it with saliva and pushes it down the esophagus into the crop, where it is stored before moving on to the gizzard. There it is crushed and ground apart before moving into the intestine, where it is broken down further by digestive enzymes. Some of the food is passed into the bloodstream for use by the earthworm, and the rest passes out the anus as castings (worm poop).
Do earthworms have eyes?
No. They have receptor cells in their skin that are sensitive to light and touch. They will move away from light because heat from the sun or a light source will dry out their skin and kill them.
How do earthworms breathe?
Earthworms do not have lungs; instead, they breathe through their skin. Their skin needs to stay moist to allow the passage of dissolved oxygen into their bloodstream. Earthworm skin is coated with mucus, and they need to live in a humid, moist environment.
How do earthworms move?
Earthworms have groups of bristles on each segment of the body that move in and out to grip surfaces as they stretch and contract their muscles to push themselves forward or backward. They tend to move forward.
If an earthworm is cut in half, will it regenerate into two worms?
No. The half with the worm’s head will survive if the cut is after the segments containing vital organs. But the other half will not grow a new head nor other vital organs.
Which end is the head?
The head is at the end closest to a swollen band encircling an adult earthworm.
What is that swollen band?
The swollen band is called a clitellum. After copulation, it secretes a cocoon in which eggs and sperm are placed for conception and development.
How do they reproduce?
Earthworms are hermaphrodites, so individuals have both female and male organs. They mate by aligning themselves in opposite directions at their gonadal openings and exchanging packets of sperm. Each earthworm will form an egg capsule in its clitellum and pass it into the environment. The egg capsule is golden brown and looks like a tiny lemon the size of a match head. Two to seven Eisenia fetida babies (three, on average) will hatch from an egg capsule in 30 to 75 days.
Can earthworms survive the winter outdoors?
To survive winter, other species of earthworms can burrow into the soil below the frost line. But composting earthworms don’t burrow, so they produce cocoons that allow their babies to live through cold weather. People who are vermicomposting can counteract cold by insulating their worm bins.
How long do worms live?
The Eisenia fetida earthworms’ life expectancy is approximately 4½ to five years.
Will the worm population in a bin keep growing?
If the bin has the proper conditions (i.e., moisture level, temperature), the earthworms will thrive and reproduce. After about four to six months, you may need to thin the population. Do not put the worms in your yard because it is not their natural habitat and they probably will not survive.
For more information, see here.