A monarch butterfly grows up in four stages: egg, caterpillar, chrysalis, and adult butterfly. The egg hatches about four days after it is laid. The new caterpillar eats its own eggshell first. Then it starts on milkweed leaves.

A growing caterpillar outgrows its skin. It sheds the old skin and grows a new one. This is called molting. Then a full-grown caterpillar hangs upside down in a J shape. It sheds its skin one last time. Under it is the green chrysalis.

A new butterfly comes out of the chrysalis with crumpled wings. It must pump fluid into them and let them dry before it can fly. Going through all four stages, egg, larva, pupa and adult, is called complete metamorphosis.

Most frogs come out of eggs as tadpoles. Tadpoles have gills and a tail, like little fish. They eat a lot to fuel their change into frogs. As a tadpole changes into a frog, it grows lungs and loses its gills. Then it can breathe air.

A hen's egg takes twenty-one days to become a chick. Before it hatches, a chick grows a small, sharp egg tooth at the tip of its beak. It uses the tooth to peck through the shell.

Songbird chicks are helpless, with eyes closed and almost no feathers. They stay in the nest and wait for their parents to bring food. A young bird that has left the nest but cannot yet fly well is called a fledgling. A fledgling hopping on the ground is usually fine. Its parents are close by and feeding it, so the best thing to do is leave it alone.

A newborn kangaroo is only about the size of a jellybean. It crawls into its mother's pouch by itself, using its front legs. A baby kangaroo is called a joey. It keeps drinking its mother's milk until it is about 10 to 12 months old.

A newborn giant panda weighs only about 1/900th as much as its mother. It is the size of a stick of butter, and it is pink and blind. A cub cannot move around much until it is about three months old. By three to five months it walks pretty well.

A baby sea turtle hatches from an egg buried in the sand, then crawls across the beach to the sea. Hatchlings find the sea by the slope of the beach and by the moon or starlight shining on the water. Bright lights from people can confuse them. Young sea turtles then swim out to the open ocean, where they live for several years.

Words to know

• chrysalis: butterfly's resting case
• molting: shedding skin
• fledgling: young bird
• metamorphosis: big body change
• hatchlings: newly hatched babies

The short version

Baby animals grow up in stages. A monarch butterfly goes through four: egg, caterpillar, chrysalis and adult. Most frogs come out of eggs as tadpoles and change into frogs, growing lungs and losing their gills. A joey is about the size of a jellybean at birth and drinks milk for 10 to 12 months.

Quick facts

• A monarch butterfly grows up in four stages: egg, caterpillar, chrysalis, and adult butterfly.
• A growing caterpillar sheds its skin in a process called molting.
• As a tadpole changes into a frog, it grows lungs and loses its gills.
• A hen's egg takes twenty-one days to hatch into a chick.
• A newborn kangaroo is only about the size of a jellybean.