Metamorphosis, A Caterpillar's Life
By Joan Whetzel
Every spring, those hairy, worm-like, creatures with legs appear on tree branches. Each of these caterpillars look as different as the butterfly they morph into, and their life spans can range anywhere from 1 month to 1 year. However, they all go through the same stages of metamorphosis: egg - to larva, or caterpillar - to chrysalis, or cocoon - to butterfly.
The Egg Stage
The first stage of a caterpillar's life begins as an egg, which is quite small and can either be round, oval or cylindrical in shape - depending on the type of caterpillar and butterfly it will become. The eggs are laid on tree leaves, but not just any tree leaves. They are laid on the specific type of tree leaves that the newborn caterpillar will need to eat to grow bigger, the kind of tree leaves that their species likes to eat most.
The Larvae Stage
The second stage of life begins when the caterpillar hatches from its egg. This is the stage of eating mass quantities of leaves and rapid growth, both in length and in girth. When it first hatches, it is very, very tiny, which means they can't really travel very far to find food. So it must begin by eating the very leaf on which it hatched from its egg. They move on to nearby leaves, eating and eating and eating its way along the tree or bush branches. They grow rapidly, like human children, as they seem to eat everything in sight. Yet, caterpillars have a skin, much like a snake skin, which does not grow. So they must molt, or shed their skin, several times during the caterpillar stage of life.
The Cocoon Stage
The caterpillar enters the third stage of life once it has reached its full weight and length, at which point it spin themselves a chrysalis (a.k.a. a pupa or cocoon). While inside their snug little cocoon, they are changing from a pocket-sized, thick, worm-like bug with lots of legs and without wings into a beautiful flying insect called the butterfly. This is the process known as metamorphosis, which can be defined as an rapid and complete transformation in shape and appearance of an animal.
The Butterfly Stage
The caterpillar begins its fourth stage of life when it emerges from the chrysalis as a butterfly. This is the adult stage of life. When it first comes out of the cocoon, the butterfly's wings are folded close to the body and are quite soft since they had to be folded up so close to its body while in the chrysalis. Upon emerging, the butterfly hangs from the tree limb, and stretches its wings, allowing the blood to pump through them. It begins flapping its wings in preparation for flight 3 to 4 hours later. Once the butterfly begins flying it goes in search of a mate so that it can lay its own eggs, and begin the whole process all over again.
Witnessing the Life Cycle First Hand
The caterpillar's life cycle can always be observed out in nature, if you know where to look for the butterfly species in your area. The life cycle can also be learned about in books and films and on websites like these:
· Metamorphosis
http://www.thinkingfountain.org//m/metamorphosis/metamorphosis.html
· Butterfly and Moth Life Cycle
http://www.kidsbutterfly.org/life-cycle
· Discover Life. Caterpillars Identification Guide
http://www.discoverlife.org/20/q?guide=Caterpillars
One other way involves the purchase of live butterfly kits. Depending on the kits, it may or may not come with the caterpillar or eggs. For those that provide only the basic kit, the kit includes the order forms for the live eggs or caterpillar to be delivered to kit owner. Many schools use these as learning projects for their students. The best part of the kits is that the kids not only get to witness nature first hand, they get to learn how to be responsible for the life another living thing, and at the end they get to release the butterfly back into nature.
References
The Butterfly Site. Butterfly Life Cycle.
http://www.thebutterflysite.com/life-cycle.shtml
Cook, Julie and Elasha Morgan. Utah Education Network. From Caterpillars to Butterflies: Life Cycles.
http://www.uen.org/Lessonplan/preview.cgi?LPid=702
Monarch Butterfly USA. Monarch Life Cycle.
