How many parts can the worm be cut into as much as possible, leaving it functional?

Let’s consider an example of an earthworm, since it is the most common and found in our area. If you split it in half, then one part of it will die. Only the half will remain alive where the belt is located (seal from one part of the earthworm). The closer the incision is to the girdle, the less chance the worm has to survive. All due to the fact that the heart, the nervous system, the digestive system and so on are located there. These systems are located throughout the body of the worm, but their main parts are located in the front of the body. But it’s best not to do such experiments.