Growth

Babies can't stay babies all their lives!

They have to grow up! When first born, human babies are completely dependent on adults for everything - food, water, shelter, clothing.

Humans grow from babies to children to adolescents, and finally stop growing when all the bones in their skeleton have finally fused between the ages of 16 and 18. This long childhood takes a lot of care and support from adults.

Compared with most young animals humans have a very cushy life.

Birds are encouraged to leave the nest as soon as they can fly and gather food for themselves. And most animals that live in the sea don't have any contact with their parents at all - they have to survive by themselves from day one.

Fact file

Name: Parrot fish
Group: Fish
Habitat: Coral reefs in tropical seas

As babies: They have a period of drifting in the oceans as plankton with many other tiny organisms. Their parents take no care of them and remain living on the coral reef.
Other changes: Parrot fish often go through different colour stages as they grow.

Need to know: Parrot fish start as females in almost all species, eventually becoming males after breeding several times as a female.

Fact file

Name: Australian bee eater
Group: Birds
Country of origin: Australia

As babies: They hatch from eggs. Their parents only lay a small number of eggs, so they can take good care of their babies until they leave the nest.
Other changes: Some baby birds are born naked - they grow feathers quite quickly though!

Need to know: Baby birds have a small tooth at the end of their beak - they use this to break open the eggshell when they hatch.

Fact file

Name: Blue swimmer crab
Group: Crustaceans
Habitat: Warm coastal waters

As babies: They hatch from eggs and have several larval stages. Their parents lay hundreds of thousands of eggs and do not care for their babies at all.
Other changes: Crab larvae look very different to the adults they grow into!

Need to know: The back legs of these crabs are modified - they look like paddles, allowing the crab to swim.

How do we grow?

Like other mammals, humans grow at a fairly steady pace until they reach adulthood. Every day as they get older their bodies are changing. Their skeleton grows with them, each bone getting bigger over time.