Will the circle be unbroken,
By and by, Lord, by and by
There’s a better home awaiting
In the sky, Lord, in the sky
“Will the Circle Be Unbroken?”
For the last few chapters, we have looking deep, deep inside of creatures, to see what they are made of, what makes them tick. Now that we have a better grasp of what creatures are like in their very insides, we are going to come back to our creature houses – the homes where each species of creature lives. Inside the creature homes, there might be members of different ages, just like your family, all growing and changing – mothers and fathers, children and teenagers, elders and babies.
Life among all creatures is like a circle known as the life cycle. In it, creatures are born, they grow, reproduce (have children), and eventually they will die. Their offspring (those children that they had) will continue the cycle, however: they will grow and reproduce, and then their offspring will grow and reproduce, and then their offspring will grow and reproduce, and on and on. Remember that growth and reproduction are two things that make something a creature, and in the next few chapters, we will be exploring the Kingdoms of Creation once again to see the wonderful variety of these activities.
There are two main ways that creatures reproduce: they either have a mother and a father or they have to do without. Going through life without parents would be very difficult for us, but it is not a problem at all for the denizens of the Kingdoms of Bacteria and Archaea. These little unicellular creatures reproduce by splitting themselves in half!
When a new bacterium (that’s the singular of bacteria – shall we call ours Ebeneezer?) is born, it first goes about the business of living: respiring, excreting, getting nutrition (looking for food or producing food), and moving around in response to their environment. At a certain point (a predictable amount of time as ordained by the Creator), Ebeneezer will start to grow and elongate (become like an skinny oval). Its DNA will copy, and then it will split into two new bacteria (we’ll call them Frederick and Gregory). Fred and Greg are exact copies of each other – like identical twins. But even more than this, they are exact copies of Ebeneezer. When bacteria reproduce, they do so by making two exact copies of themselves. This type of reproduction has the advantage of increasing the number of bacteria quickly (for many bacteria, they double their number every 20 minutes, going from one to millions in just 7 hours!).
Reproduction without parents is not unique to the Kingdoms of Archaea and Bacteria. Parents are lacking in much of the Kingdom of Fungi, although many members don’t split to reproduce but use something almost like a seed called a spore, as we will see later. As usual, the residents of the Kingdom of Protists are most varied and unusual, with some having parents, while others will split in two or bud (have many “children” that break off of a “parent” cell). There are even some in the Kingdom of Plants and Animals that can reproduce without two parents – a curiosity that you will encounter if you continue to explore.