Watching a caterpillar change
Biology · Early Years · The School
Watching real change
Some classrooms keep real caterpillars. They live in a tank. You can watch them for weeks. This is not a video. It is not a picture. It is a real, living thing. It changes right in front of you, a little more each day. Watching it happen for real teaches you far more than being told about it.
Four things you would see
First, a tiny EGG. Then a CATERPILLAR hatches out. It eats and eats. It grows fatter each day. Then it goes very still. It forms a hard case. This is called a CHRYSALIS. It hangs still. At last, the case cracks open. A BUTTERFLY climbs out. Its wings are soft and crumpled at first. Slowly, they dry and go stiff.
Not just "getting bigger"
A puppy stays puppy-shaped as it grows into a dog. Four legs, a tail, fur, the whole time. A caterpillar does something much stranger. Inside the still case, its whole body rebuilds itself. What climbs out has wings. It has six thin legs. It looks nothing like the caterpillar that went in.
DAY 1: a tiny caterpillar. It is barely as long as your fingernail. It nibbles a leaf. DAY 10: the same caterpillar is much fatter now. It has eaten a huge pile of leaves. DAY 14: it hangs still, upside down. It forms a hard green case. It does not move for over a week. DAY 24: the case goes dark. Then it cracks. Something climbs out slowly. Its wings are crumpled and damp. It looks nothing like the caterpillar at all. By the afternoon, the wings have dried flat. It flies.