Richard Hines, age 7., of Arroyo Grande, CA.; for his question:
If a worm is cut will both halves grow?
If you break a leg, the bone will grow together again but if you lose a leggy you cannot grow another one. The earthworm has no legs to break or lose. But his small body is very clever at mending other wounds. It can re grow a lost tail, and it can even replace a lost head.
When you are older you may go to a biology class to study the plants and the animals. You will see tiny wonders enlarged under the microscope. You will learn other things by doing experiments. Perhaps you will study a live earthworms right there in class. The teacher will be there to help you learn something amazing about little mr. Pinky, this experiment calls for surgery for the living earthworm must be cut into two halves.
This experiment cannot be done by just anybody for the worm must be sliced in just the right place or the operation will not succeed. Your biology teacher will know that the worm is an annelids which means a ringed animal. The rings are those grooved bands around his long body, all the way from his head to his tapered tail, and are called segments.
Before the operation begins, you must count the segments around the patient's wormy body. Begin at the head and count to segment number five. Continue counting until you come to segment number l8. Now you know where you can safely operate. The worm must be sliced in half at some point between the fifth and the l8th segment.
If a cat or a dog is cut in half the damage is fatal, but the gentle, little earthworm has a special gift for mending his body. If the slicing operation is done at the proper place, the two halves of his wormy body will heal. What's more, both halves will start to grow. The tail half grows a new head, and the head half grows a new tail, and one earthworm becomes two earthworms.
A human hospital has a special surgery room. When a patient is operated upon, a trained team of doctors and nurses work together. So let's not operate on mr. Pinky without proper help. With the help of your biology teacher, the worm can be cut in halves and become two worms, but without the proper team of experts, the operation might fail.
If the cut is made in the wrong place, the worm operation would be only half successful. Suppose the little patient is sliced behind the l8th segment. The head end grows a new tail, so the patient survives, but instead of growing a new head, the tail end grows another tail. It has a tail at both ends. The poor patient soon. Perishes from hunger, for without a head he cannot eat.