Peter Dryke, age 9, of Duluth, Minnesota, for his question:
How are earthworms born?
A human baby, of course, has a mother and a father. So does an earthworm. But his family life is much more complicated than ours. .His mother also happens to be the father of some of his brothers and sisters. And his father is the mother of some more of his brothers and sisters.
Every full grown earthworm is meant to be both a mother and a father. When you want a brood of new baby bunnies, you must start with one male and one female. The two parents must be of different sexes or they can have no baby bunnies. The same thing is true of cats and dogs and other everyday animals. But the family life of the earthworm is very different. If you want a batch of baby worms, you will need to start with two parents. But you do not have to choose a male and a female to start a new family. Any two worms you find in the garden will do. Both of them can be mothers and also fathers.
This kind of family life is hard for us to understand. In our world, boy's and boys and girls are girls. Men become fathers and women become mothers. In our world, we move around a lot and meet a lot of other human beings. Teenagers go dating and grown ups go courting. But the world of an earthworm is very small. He does not travel far or meet a lot of other worms. Choosing a wife is not easy. But Mother Nature has a plan for such problems. When any two grown up earthworms chance to meet, they can start a family. Both become mothers and go off to lay their eggs. Each mother is the father of the eggs laid by the other parent.
Soon after the parents meet and part, each one grows a pale, puffy band around its wormy body. This narrow ring is a cocoon of eggs. When the tiny eggs are ready, the parent worm wiggles backwards and slips the cocoon forward and over its head. The small sack is. left behind on the ground. But the eggs inside have plenty of yolk and egg white to nourish them. As a rule, one egg is stronger or hungrier than the rest. It feeds upon the other eggs in the cocoon.
After about three weeks, the sturdy young earthworm is ready to hatch. It worms its way out of the cocoon, leaving the husk behind. The youngster is a small copy of its parents of both of them. Meantime, its father laid a cocoon of eggs and from it hatched another baby worm. The youngsters are not likely to meet each other or their parents. So they do not have to figure out which of their kinfolk is which. The parents may not meet again. But after each one lays a batch of eggs, it grows another and then another cocoon. Each parent may go on producing baby earthworms, one after another, all through the warm, moist spring and summer seasons.
The world of nature teems with small and simple animals. These creatures far out number us and they were on earth millions of years before the human family arrived. Many simple animals have family lives like the earthworm. Other tiny creatures have only one parent.: All by itself, the parent hands on life to a new generation. Then there are many tiny one celled animals who multiply by dividing. Each parent separates its small body into two equal halves and so it becomes a brand new pair of twins.