Original air date: 2 November 2011
Below is a graphical presentation of what happens in the episode

The text version of the timeline gives a more detailed look at the programme

Selected material
The 14-year-old caterpillar (24’30-27’45)

The wooly bear caterpillar takes probably the longest time until it can change into an adult moth (bottom). The problem is caused by very short summers in the Arctic as well as its plant food producing poison in its leaves to make them inedible. It can only eat very little each year before it is forced to prepare to hibernate for the coming winter (top).