Simple behavioural responses in Woodlice

Today we have been setting up Choice Chambers for Woodlice.  A choice chamber is what it says it is; we provide the Woodlice a choice of environment, then observe where is 'chooses' to go.  Of course, the wood louse is of such little brain that there is not really any thinking about it, and therefore not really any choosing. It is a simple response to a stimulus.  ( a stimulus is a detectable change in the environment).

We decided to find out if our Woodlice prefer dark or light conditions. We set up a choice chamber, essentially a large Petri dish, with one half covered in a black bag and a bright light on the other half.  We introduced ten Woodlice and gave them five minutes.  Then we recorded how many were in each half, and were able to do a chi-squared statistical test on the results.

Most liked the dark conditions. This is a simple behavioural response in which the wood louse exhibits a kinesis. In response to the stimulus, light, it increases its rate of movement.  We observed them scurrying around madly in the light.  This is not so mad as it may seem.  By moving around they are more likely to find their preferred conditions (dark) more quickly. And when they get there, they slow down and stay there.  

If you are a wood louse, it may be a matter of life or death.  If you are under a log or stone, it may be dar, but you can't be seen by predators ( birds) If some unthinking human goes and exposes you, you better run like the clappers.