Why do insects shed their skins?

Molting is also called peeling, and for some animals with hard shells, it is also called shelling. This situation exists in arthropods, amphibians and reptiles. The outer skin of some animals cannot grow with the body, so when the body grows up, it is necessary to replace the "coat" with a fixed size on the body surface, which is called molting.

Of course, molting factors are not only related to growth, but also related to development. An insect with incomplete abnormal development will shed its skin when it emerges. Some species often have no obvious increase in size before and after molting, but only grow wings, which we will talk about later.

It is obvious that crustaceans grow up after molting. Friends who have raised crayfish and crabs often see such a scene: when molting, there will be "two" animals, one big and one small. The big one is just the "real body", and the small one is its shell that has just fallen off. For insect larvae, sometimes we have an illusion that they have not shed their skin, but have grown up a lot, such as beetles such as scarabs and shovel worms, as well as butterflies and moths. These larvae obviously don't shed their skin, but their bodies are getting bigger and bigger.

In fact, the skin of these larvae has not changed, but they put on a "new coat" with strong plasticity when they molt last time, so that when the larvae keep eating, this "coat" will be stretched like a balloon, so that they can store enough energy in their bodies for the next stage of development until the next molting.

We know that snakes, lizards, frogs and other amphibians and reptiles also shed their skins, but their molting mechanism is different from that of insects and crustaceans mentioned later. Their epidermis is the product of skin keratinization. With growth, this layer of cutin will become tighter and tighter. At this time, it is necessary to shed the original horny skin and put on a new "coat" to adapt to the newly grown body.