What do worms eat?
Worms have tiny mouths and will take extremely small bits out of things like bacteria, fungi and protozoa. The love organic matter such as plants, fruit, compost heaps of cut grass, potato peelings and decaying animals. When the food is too large for their mouths they moisten it to make it soft and suck it in.
Worms have no teeth and the "gizzard" does all the work. Grains of sand or soil are ingested along with the food and a grinding process occurs. When the food leaves the worm's gizzard, it goes into the intestine and is dissolved and absorbed into the worm's blood.
You cannot cut their head off earthworms or cut them in the middle to try to grow two worms. Cutting off any vital organs will kill them. However, if you cut the tail end off a worm (not advisable), then they will grow another one.
Worms are essential in gardens because they keep the soil soft, aerated, and full of nutrients which are good for your plants. When it rains hard, worms will surface to the top of the soil if there isn't enough airspace for them to get oxygen.