The skeleton inside you
Do you think skeletons are scary? Many people do. They think of the skeletons that jump out at them on a ghost train in a fairground, or they imagine skeletons they have seen in films or in cartoons, which jump out of the dark and scare people. Most people think of skeletons and bones to do with death. For example, you may see a picture of a camel skeleton in a desert or see a film of vultures picking among the bones of a zebra on the grassy plains of Africa. The truth is that bones are not to do with death, they are living parts of the body. Skeletons cannot jump about and scare you. Bones cannot move on their own. The parts of the body that move the bones are muscles.

Bones have three important tasks in the body. They hold you up, protect some of your body parts and help you move. Just feel the bones in your hand, wrist and forearm. Wriggle your fingers and turn your palm up then down. Image what it would be like if you did not have any bones. Your fingers, wrist and forearm would be soft and wobble like jelly when you tried to move. As you sit reading this your heart beats in your chest, your lungs swell and shrink as you breathe and your stomach and intestines digest your last meal. If you did not have a backbone and ribs all these parts of the body would squash together and would not be able to work.

There are two hundred and six bones in an adult body. You may think this is rather a lot and perhaps the skeleton could work with fewer bones. The reason there are so many bones is that they allow the body to move in a variety of ways and be flexible. To see the importance of flexibility just try this experiment. Hold out your hand, then curl your fingers in until they touch the palm. Use this movement of the fingers and the movement of the thumb to pick up a pen. Now imagine that instead of the three bones you have in each finger you had only one. Try the experiment again and see how much more difficult it is to pick up the pen.

We have already mentioned the bones of the camel and the skeleton but other animals have skeletons of bones too. Fish have a skeleton made of a large skull and a long bendy backbone. There are small groups of bones too, which support the pairs of fins at the front and back of the body. Frogs, toads and newts have skeletons of bones. Each skeleton has a skull, backbone, ribs and limb bones. Reptiles such as lizards and crocodiles have similar skeletons to newts. Birds have a very distinctive skeleton, which has a large hipbone and arms without many finger bones. These features help the bird to fly. We belong to the group of hairy-skinned animals called the mammals. In this group are animals ranging from small mice to huge whales. Every one in this group has a skeleton of bone.

You may think that all animals have bones but you would be wrong. Most animals survive without bones but they still have a skeleton. Worms and slugs have water inside them to give them support, while crabs and lobsters have hard shells. Some animals, like snails, have both a watery skeleton inside them and a hard shell to protect them.

Skeletons are not scary they are a vital part of every animal.

Do very tiny animals have skeletons?
There are some animals that are so tiny that you need a microscope to see them. Many have water inside them to give them support. Some have tiny shells around them. When some of these tiny-shelled animals die their shells collect together and form a rock called chalk.

How can water act as a skeleton?
Water can give support just as a bone does. Water is a liquid and one of its properties is that it cannot be squashed. You may have heard about waterbeds. A waterbed is made from a mattress which is full of water. People can rest on it and sleep without the bed bursting. The water is strong enough to support their weight. If you watch a slug moving along the ground, it keeps its shape and can move its muscles because it has a bag of water inside it to give it support.

Which parts of the skeleton give protection?
The skull protects the brain, the backbone protects the spinal cord and the ribs protect the heart and the lungs.

Is the backbone made from just one bone?
No. It is made from twenty six bones. People find it easier just to refer to all of them as the backbone. Some people call the backbone the spine.

What is the spinal cord?
This is made from nerves. They connect the brain to all parts of the body. The nerves carry messages from places such as the eye and skin to the brain and the brain sends messages along nerves to the muscles to make them work. The messages are in the form of tiny currents of electricity.

Does a tortoise have a backbone?
Yes, it does. The backbone runs along under the top of the shell. Tortoises are unusual in having extra bones, which make shell. The bones are broad and flat and are stuck firmly together. They are covered by large scales of horn. The shell of the tortoise gives extra protection to the parts inside the body. It also makes the body less flexible. If you watch a tortoise walk it plods along. Lizards can scurry along much faster as they can move the length of their body from side to side, like a fish, to give themselves extra power.

Is a crab's shell like a tortoise shell?
No. A crab's skeleton is not made of flat bones covered in scales. It is made from a stony substance. The bones in the tortoise shell grow as the rest of the skeleton grows. The crab shell does not grow and has to be shed in a process called moulting. During this process the crab acquires a new shell which expands to form a larger shell than the old one.