An amazing life giving process in ALL insects
In this article, Rabbi Samuel Waldman discusses the miraculous process of caterpillars turning into butterflies, known as metamorphosis. This process is one of the most evident miracles of Hashem, transforming a simple caterpillar into a beautiful butterfly through an incredibly complex series of changes.
Every single insect in the world molts. What is molting? This is a process that even many adults are unaware of. Molting is the process that the insect sheds its outer skin. Why is this necessary? Well, picture a young child locked up in a suit of metal armor. After a while, it would outgrow the armor, and if the armor isn’t replaced the child will suffocate. Why? Because it’s couldn’t breathe anymore. Its lungs wouldn’t be able to expand anymore and thereby it would suffocate. Well, the same is with insects. As opposed to fish, reptiles, animals, and lehavdil, humans, which have their skeletons on the inside of their bodies, at the center of their bodies, surrounded by its organs, insects have their skeleton on their outside. (That has many benefits for the insect, but that’s not the subject of this article.) The problem is that the insect must be able to get rid of its outside skeleton called the Exoskeleton (we will abbreviate it EX) otherwise it will die of suffocation because it keeps growing and the EX gets too small to continue to contain the growing insect. There are two problems with this issue. 1- how to detach the current EX and 2- it must have an EX at all times for various reasons. So how will it accomplish removing the old EX while at the same time having the next new larger EX ready to replace it? Do you have a solution? Do you think an accident can come up with a solution to this problem? And if it came up with a solution, do you think it can pull it off mechanically in the insect? Of course NOT! So, what’s Hashem’s plan?
To understand things properly we need to see the below picture.
This whole structure is called the EX. The main parts that we will be focusing on is the top part called the epicuticle. Then below that, for our purposes is the procuticle, which is the exocuticle and the endocuticle combined. Then, comes the extremely important epidermis at the bottom. It’s amazing how this single- cell wide layer can be involved with so many parts of the molting process, as we shall explain.
The molting process has a few important hormones that are involved. What’s a hormone? Hormones are chemical substances that act like messenger molecules in the body. After being made in one part of the body, they travel to other parts of the body where they help control, in different ways, how cells and organs do their work. (Hormones, like enzymes, that we will soon mention, are VERY COMPLEX CHEMICAL STRUCTURES used in basically all the molting processes.) So, after the body recognizes that the insect has gotten too big for its current EX, the first steps of the molting process begin. (It’s not 100% clear what the signal is. Some say that the body SOMEHOW recognizes the shortness of breath by detecting a lower oxygen level in its system, or maybe it has some triggers that recognize when the body has completely filled up the available space inside it.) So, when the signal registers, the brain produces a hormone called PTTH, and it goes into the insect’s blood, (called hemolymph) where it meets up with the prothoracic gland. This triggers off the important Ecdysone hormone. Even if it never molted before, it seems to “know” that something going to happen. Therefore, at this point the insect stops eating, and it finds itself a good, protected area to molt. `This hormone enters the epidermis where it is converted into its active form, called 20-hydroxyecdysone (we will call it ecdysone – it’s easier). At this point all the action starts to take place. The first thing to happen is the very important process called Apolysis. The ecdysone hormone in the epidermis cause the cells of the epidermis to increase in size. This puts pressure at the top of the epidermis and the bottom of the cuticle where these two layers are attached. It soon breaks apart the bond between them and it opens a gap between them. This space is called the exuvial space. Once that happens, the epidermis secretes an INACTIVE special molting fluid (in some insects it’s more like a gel). Then the epidermis secretes a new epicuticle. This epicuticle will be the beginning of the new EX. This epicuticle will not yet have all its layers. An epicuticle when fully developed has 4 parts. It has the cement layer that’s all the way at the top. That’s followed by a wax layer. (These 2 layers will first be laid down later on in the process.) Below that is the outer epicuticle – and that’s this layer that the epidermis is now secreting. It plays a very important role. It will be the barrier between the molting fluid that’s now on top of it, and the rest of all the future new layers that the epidermis will soon secrete, that will go below it. Eventually it will finally form the full, new EX. (This outer epicuticle layer will be formed in a unique way. It will be formed with many folds to it, similar to the letter “S”. These folds, will unfold later on [and straighten out] during the actual molting process.) Then comes the inner epicuticle. It’s a much tougher layer and it’s not expandable at all. This is the main layer that makes molting necessary since it’s inelastic and it can’t grow. Eventually the epidermis will also secrete the material for the next lower layers – the exocuticle, followed by the endocuticle, and also the cement layer and wax layer will come about later as well, through pores, which will spread them out on top of the new epicuticle layer. So, at first the molting fluid is inactive, once the outer epicuticle is in place, a bunch of complicated enzymes and a few hormones, mainly the ecdysone hormone will trigger the activation of the molting fluid and it will start to break down the old EX. It will break everything down except the old epicuticle. That somehow remains protected from the molting fluid below it.
AMAZINGLY, (and miraculously) these broken-down pieces will filter through the molting fluid, and then through the upper epicuticle that was just laid down, and the magician epidermis, that does so many jobs, IS ABLE TO ABSORB AND THEN RECYCLE THE BROKEN DOWN PARTS and magically turn them into the new layers of the new EX! The full outer epicuticle will them be formed followed by the inner epicuticle, followed by the exocuticle and eventually followed by the endocuticle. (Sometimes, part of the lower layers are actually finished up after the full molting process has taken place.)
Once, the level of the hormone ecdysone starts to fall below a certain level, and all the molting fluid and everything else, has also been absorbed by the epidermis, that triggers the secretion the eclosion hormone which starts the final process called the ecdysis process. That is the actual process that sheds the old Epicuticle that’s still very much intact and connected to the insect. Intense wiggling and peristalsis activity begins. These movements cause the muscles that were attached to the epicuticle to break off. Then the insect will inhale a lot of air, and often it will also swallow water, each helping the insect to expand its body. When doing that, it will unfold the folds that are in the epicuticle, thus enlarging the new epicuticle to be larger than the previous one, giving it the larger needed EX than before the molt. It is soft at the time of the molt, so it’s expandable. Now, Hashem made it that there should be weak spots on the old epicuticle called ecdysial sutures, put by Hashem in very strategic places so that when the insect expands, it breaks the epicuticle at all these weak spots. This finally allows the insect to pull itself out of its, now, unattached, old epicuticle! And guess what, right below it, is the new EX! Once it’s out, the insect looks pale and whitish. It’s still soft. Over the next half a day or more, the insect is still inactive. During that time, utilizing various enzymes and protiens, the skin will start to sclerotize, which means that it will start to get its tan brownish color, and it will start to harden. During this inactive time the muscles will start to reattach to the new EX.
Of course, there’s much more to all these parts of the process, but for our purposes, it’s enough. We have written a very simple explanation of the molting process. Let me give you the description of a science book, that describes the process of molting. They write, “It involves a very complex interplay of various hormones, enzymes, and signaling molecules, that interact in a HIGHLY ORCHESTRATED MANNER, to ensure the precise timing and coordination, so that the molting process works”. “Orchestrated” indicates that this was a very thought-out, and planned, step by step, careful process, for it to work. No accident could ever bring about such a complicated process. This is MAJOR YAD HASHEM!
2 more interesting important points. The first being that for an insect to be mature enough to reproduce, it needs to go through a minimum of 3 full molting processes. If molting were an accident, then surely, even they agree it would have taken a huge amount of time – many, many, many, years – before it could develop a working molting process. However, there’s just one “small problem”. How could a single insect ever have developed, if it didn’t have enough time to get to it’s first molt? It would have died in a couple of years, never even getting to its first molt! Thereby, never having enough time to reproduce a second generation, especially, since it needs at least three molts before being ready to reproduce. This a stupendous question that they do not have any normal answer to.
Secondly, there’s another miracle that takes place. In our last article, we spoke about how in the breathing system of insects there are trachea tubes through which the insect breathes air/oxygen. These tubes need to get bigger in order to provide enough oxygen for the new bigger insect that will be the result of the molting. So, before the molting takes place, there grows a new, wider trachea tube around the current thinner trachea, however, they are not attached to each other. At the time of molting, the old thinner tubes are shlepped out of the newer, wider tubes! As the old epicuticle is being removed, the old trachea tubes are being pulled with it! Now, obviously, this causes that the insect will not be able to breathe during the last part of the molting process, and the truth is – they don’t. Here’s what amazingly happens. A little while before the actual molting will take place, the insect SOMEHOW knows to breathe in much more air than usual. It will inhale about 40% more than usual, thereby saturating all their cells with extra oxygen. With that extra oxygen, they can survive the time it takes for the trachea tubes to be pulled out, and for the new trachea tubes to reattach to the spiracles on the outside part of the insect and to reconnect to the tracheoles on the inside part of the insect. (The spiracle and the tracheoles were explained in the last article about insects.) How amazing is that!
This is a picture of an EX that just molted. You can see the trachea tubes that was pulled out with the old epicuticle.
HOW GREAT ARE YOUR WORKS HASHEM. THEY ARE ALL MADE WITH GREAT WISDOM [AND PLANNING]!
Rabbi Samuel Waldman marvels at the wonders of Hashem’s creation, noting the miraculous aspects of this process and promises future articles to explore the butterfly’s wings and migration, further revealing the intricate and wondrous design of nature.
Read the previous part of the article here.