Caterpillar starts its life as a small egg attached to the underside of plant leaf. But they are not attached to just any plant. Each species of butterfly lays their eggs on one species of plant. This really gets complicated when you consider that there are hundreds of thousands of butterfly species.
Anyway, it takes around 4 days for the egg to hatch and out comes a small, but very hungry larva. The larva eats its way out of the egg, and later the rest of the egg too. It also eats the leaf it’s on which and some neighboring leaves as well.
What caterpillars do for most of their lives is basically eat, eat and eat. As a result, they get big. Several times the initial size. They shed their skin when they cannot fit in the old one anymore. This happens several times, until the voracious fellow gathers enough resources and energy for the process of becoming an adult.
When it’s ready, the caterpillar finds a nice, comfy spot on some plant and spins itself a silk button on which it attaches. Some species weave a harness that they sit inside. There are multiple ways of attaching yourself comfortably to a branch. And comfort is very important for this long and difficult journey.
One week prior to the transformation, the caterpillar grows the future shell of the pupa underneath the first layer of its skin. When it’s all cozy and prepared, it just sheds the top layer of the skin. Pupa is there and ready to roll. Color of the pupa changes to fit with the background, camouflaging itself to escape the eye of predators. Pretty nifty, huh? Then begins one of the most magical processes in nature – the transformation.
Caterpillar releases enzymes and literally digests all of its tissues. As a result, the whole body of the caterpillar becomes a soup of proteins. How does this soup become a butterfly? We don’t know yet. Any probing to see what’s inside can interfere with the transformation. However, scientists have figured out that not all cells liquefy, some remain solid. They suggested that these cells, called the imaginal discs, are the ones who do the differentiation of the soupy goo. How do these discs actually do that, still remains a secret.
The process of transformation lasts around 2 weeks. Caterpillar that began the process and the butterfly that flew out of the pupa are two totally different creatures. They move differently, perceive the world through different senses, feed in two very different ways, etc. but they are the same creature. Most fascinating thing is that the butterfly keeps the memories of being a caterpillar. Some would think that turning your neural system into a soup would definitely erase your memories, but it’s not the case. A study was performed on tobacco hornworm caterpillars. Scientist trained the caterpillars to avoid certain smells by shocking them while exposed to that smell. Those individuals were again exposed to the smell after their metamorphosis and the results were astounding. The butterflies also avoided the smell, suggesting that they have memories of their youth.
We have absolutely no clue how this happens. The ways of nature are mysterious and weird. Aside from being incredibly interesting, the metamorphosis leaves us with a symbolic message. The world we live in sometimes asks of us to self-destruct and start from scratch, but at the end, you will still be you. Probably even a better version of you, if you prepared and worked hard like a caterpillar.