Image for Split personalities

Split personalities

Duration: 01:41

Why do butterflies have such weird and wingless offspring as caterpillars? The answer is because their life is split in two. One part is for eating, and one for breeding. A caterpillar's only purpose is to eat and grow, so wings would just get in the way. A caterpillar can balloon to an incredible 2,000 times its starting weight. That is like a human baby gaining eight tonnes in a month and becoming the size of a bus. Once it has finished gorging, the caterpillar uses all those calories to transform from ugly bug to winged beauty. The adult - the butterfly - has a very different mission. It needs to attract a mate and lay its eggs far and wide.

Available since: Mon 14 Feb 2011


Nigel BEAN

This clip is from

Journey of Life AIRBORNE

Steve Leonard discovers how living things first grew wings and how all flying animals are descended from 4 ancestors that acheived the miracle of flight.

First broadcast: 05 May 2005

Image for AIRBORNE Not currently available on BBC iPlayer

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