The Moult - A poetical biological tale about moving on

Chordates, animals with spinal-cord, exhibit continuous growth. It may faster or slower, but because it is continuous, is hard to see.

Arthropods, in turn, do not have bones. Its skeleton is external and called exoskeleton. Imagine a medieval knight: his armor is a perfect example of exoskeleton.

Back to the arthropods. Among them, there are a number of nasty bugs, but some cute animals too. The ladybug is an arthropod. Because of their external skeleton, arthropods cannot grow continuously. They growth discontinuously, from time to time. Because we all need to grow, even prawns.

The growth period of these animals is appropriately called molting, because the actually replace their exoskeleton. Besides serving as support for muscles to attach and allow these animals to move, it also works as a bark, a shield. Protection. And again the armor of medieval knight lends itself to comparison.

But how does it moult? The animal has to released it. Let it go.

Differently from the medieval knight, however, all animal muscles are attached to its armor. And to lose it... it hurts!

And yet... it releases it. Because everyone needs to grow, even sand fiddlers.

It is then, at the time of exchange, that the animal becomes more vulnerable. Without its armor it is unprotected and an easy prey. Not to be left at the mercy of predators, generally animals hide during that period. They may also suffer from Tight Heart Syndrome. It looks like the human heart attacks, but it does not kill. The heart grows too fast and is still within the tight old chest. The pain is so great that it goes to the stomach (it is recommended to leave the animal quiet at this time).

Moult is a risky process. But even so… it moults. Because we all need to grow, even dragonflies.

But the moult is also a beautiful process. A flood of hormones (which were inside the animal, but it did not even knew) takes over the body, signaling that it's time to change. And when hormones are in command… you know… there is very little one can do.

After release of its shell, the animal grows, changes. The new exoskeleton, however, is produced slowly. They can often use things from the old shell (important proteins, nutrients and some good memories) and leave other things that at time seem less important (basically metabolic wastes and other bitter), but it will never be enough again to contain the animal. And that's why we all need to grow, even the cicadas.

You may wonder why, the animal does not build its new armor before discarding the first. It is because they never know how big will be the change. They never know how much they will grow. It depends on the weather, food availability, depends on the DNA ... and depends on hormones (and as we know, everything depends on hormones is... unpredictable). But it takes the risks. For it is worth. Because we all need to grow, even centipedes.

The moult can do amazing things. If any part of the old exoskeleton was lost, it returns in the new exoskeleton. In fact, it grows again in the period in which growth takes place.

A new shell can erase the damage from previous battles.

The moult is risky, but for many reasons it is worth. Mainly because all we need to grow, even butterflies.

Sometimes, because of uncontrolled hormones (bloody hormones) the animal can stand long periods without change. Or you can try to grow without changing. This causes cracks in the exoskeleton that are much more painful than the moult itself. And then it sees that one way or another, it has to change. You cannot fool hormones.
We all need to grow, even the Mantis God.

But this means that, the animal (as the animal it is) work so hard to build a protective armor, its perfect size and shape; And still run the risk of being eaten in the process; cares to connect all of its muscles to it, stay there, warm, quiet and protected just to… eventually moult again??

It seems strange that one would want to do that. But who knows what goes inside the head of a moth? Maybe it is good to have a bigger house. Perhaps the brightness of shiny new exoskeleton is seductive... who would know?

What we can be sure is that we all have to grow. And all we have to moult in order to grow. Even ourselves.

Excerpt from the book 'The Truth about Dogs and Cats'. Back to the syllabus