If you didn’t have a skeleton inside you, you’d need one on the outside of you.
It would be like a little suit of armor. That’s how insects are built. We call that skin an exoskeleton. It’s hard, so insects can’t grow little by little. Instead, they grow in spurts when they shed their skin. When the old skin becomes too small, a soft new one forms below it. The old skin splits down the back. Then the insect crawls out. Pretty soon, the new skin expands and turns hard. An insect could change its skin four or five times before it becomes an adult and stops growing. These changes are called metamorphosis.