Comparing the life cycles of an insect, a bird and a mammal
Biology · Key Stage 2 · The School
An insect that changes completely
A butterfly starts life as an EGG. It hatches into a CATERPILLAR. The caterpillar eats and grows. It then forms a CHRYSALIS. Inside, its whole body rebuilds. What climbs out is an adult BUTTERFLY. It looks nothing like the caterpillar it once was. Many other insects go through a similar change.
A bird's life cycle
A bird also starts as an EGG, laid in a nest. It hatches into a CHICK. A chick looks like a smaller, fluffier bird. It does not look like a totally different creature. The chick grows feathers over time. Slowly, it becomes an adult bird. Its parents feed it during this whole time. Most chicks cannot fly or feed themselves for quite a while.
A mammal's life cycle
A mammal works differently again. It does not hatch from an egg outside the body. It grows inside its mother instead. This time is called gestation. The baby is born alive. It already looks like a small copy of its parent. It just grows bigger over time. Most young mammals also drink their mother's milk for a while after birth.
The butterfly is the odd one out here. It changes its whole body shape. It goes from caterpillar, to chrysalis, to butterfly. This total change has a name: METAMORPHOSIS. The bird does not do this. Neither does the mammal. A chick already looks like a small bird. A baby mammal already looks like a small version of its parent. Only the insect has a stage that looks nothing like the adult it will one day become.