People can refer to many different kinds of changes as metamorphoses, like drastic makeovers, for instance. But in science, the term 'metamorphosis' refers to a change that an animal goes through as it grows older. The change has to be significant (that is, it has to be really big!)--the final life stage bears no resemblance to the others. For example, humans don’t go through metamorphosis because babies have the same physical structures and functions as an adult would.
Many amphibians also go through metamorphosis. They start their lives in the water with gills and a tail to swim around with. As they get older, the lungs form to replace the gills and legs start to develop so they can walk (or hop) on land. For frogs and toads, the tail gradually shortens until it is nonexistent.
Life Cycle of a Butterfly
An adult female butterfly will often lay her eggs on the underside of a leaf to protect them from predators. There, the unfertilized eggs wait for a male butterfly to fertilize them so they can begin to form and hatch as larva. The word larva refers to the growth stage of all insects with complete metamorphosis; caterpillar refers only to a butterfly or moth in this stage.
Caterpillars have three distinct body parts: head, thorax, and abdomen. As the caterpillar grows and becomes too large for its skin, it molts, or sheds its skin. Just before they pupate, caterpillars spin a silk mat from which they hang upside down. The silk comes from the spinneret on the bottom of the head. As it sheds its skin for the last time, the caterpillar stabs a stem into the silk pad to hang.
When it emerges from its chrysalis, its wings are small and wet, and the butterfly can’t fly yet. It has to pump fluids from its abdomen through the veins in its wings to stimulate the wings to expand to their full size. Next, the wings dry and the butterfly must exercise flight muscles before it can fly. After a couple of days, the butterfly is ready to mate and the cycle begins again!
If butterflies interest you more than frogs, there’s also the Butterfly Garden from Insect Lore*. This kit comes with a pop-up mesh habitat, live caterpillars in a cup, and a feeding pipette. The caterpillars already have the food they need in the cup, so they won’t need anything from you until they hang upside down from the top to form chrysalides. Once they have hardened, you can gently remove the top of the cup and place it in the mesh habitat. After about a week, the Painted Lady butterflies will emerge.
*Grow-A-Frog, Insect Lore and their associated companies are in no way affiliated with Discovery Express Kids. Recommendations made on this page are unsolicited, and represent popular choices by our teachers.
Williams, Laurie. “Butterfly Life Cycle”. Released into the public domain. Uploaded on 6/13/17 from publicdomainpictures.net
“Rana Temporaria Spawn”. Released into the public domain under the Creative Commons Attribution Share-Alike 3.0 License. Uploaded on 6/13/17 from commons.wikimedia.org
Pinckard, Christina. “Caterpillar on Leaf”. Released into the public domain. Uploaded on 6/13/17 from publicdomainpictures.net
McCarty, Megan. “Enclosing Monarch”. Released into the public domain. Uploaded on 6/13/17 from commons.wikimedia.org
Black, Keli. “Exploring”. Released into the public domain. Uploaded on 6/13/17 from pixabay.com