Question

I need to why caterpillars need to shed there skin when they grow bigger but we humans do not

Answer 1

Humans shed their skin all the time - just at once

A caterpillar’s ‘skin’ is actually its exoskeleton, made of a hard material called chitin. As the caterpillar grows, it’s exoskeleton does not grow with it. Instead it develops a new exoskeleton underneath, which is softer. A time comes when the old exoskeleton can no longer stretch to accommodate the caterpillar’s growth - it's the old ‘skin’.

Human skin is far more flexible, and it comes in two parts. The dermis is the inner, living skin, in which are the root hairs, oil glands and sweat glands. The epidermis is the outer ‘dead’ skin, which is made of dead dermal cells. Bits and pieces of the epidermis fall off all the time - while bathing, while washing hands.etc The pieces are so tiny you can’t see, the epidermis falls off in larger pieces - which we know as dandruff.

Answer 2

Caterpillars are required to she'd thier skin because of two reasons :

1. To form a cocoon

2. Or to remove outer exoskeleton.

Since, here 2 is more appropriate.

We humans don't have such system of shedding skin, we can remove dead cells by some way like bathing, etc.