Invertebrates have their skeleton outside their bodies. This exoskeleton protects the animal like a suit of armour. However, it does not grow with the animal so it must produce a new one as it gets bigger, rather like a new set of clothes. A bronze bug has grown out of its old skeleton, so it wriggles out and waits for its new skeleton to harden in the sun.

First broadcast:
8 October 2007

First show the clip to the class, then present images of different animals. Ask the children to group them, perhaps starting with vertebrates and invertebrates. Then ask them to come up with more detailed characteristics, for example, for mammals, birds or amphibians. The clip could be used to spark some creative writing. Show the first image of the clip and invite the pupils to choose one of the animals and write a diary for them, describing how they might feel when they grow (such as when the skin is getting too tight for them) or how safe they might feel when being attacked by other animals.