But I never really had the opportunity to experiment with a real earthworm--all the worms I dug up from my garden ended up as fishing bait.
Like most other animals, the humble earthworm has a head and a tail. Since earthworms have no eyes, the only way to identify its head is by looking at its clitellum.
The clitellum is a saddle-shaped, swollen area that is about 1/3 of the way back on a worm's body. This part, according to wikipedia, functions as the storage area for the eggs of the worm--it secretes mucus to form the cocoon which will hold the worm's embryos. The head of the worm is always located on the end of the worm closest to the clitellum.
|See that clitellum there? Image: en.wikipedia.org|
The head of the worm may survive and regenerate its tail if the animal is cut behind the clitellum.
To answer that, we have to look a bit at the anatomy of an earthworm.
It's not all perfect though. The newly generated part will be slightly smaller in diameter than the original segments and sometimes a hue lighter in color.