6.1.6 Causes of Animal Movement

Investigating Environmental Factors That Cause Animal Movement

Environmental factors can be abiotic or biotic
Abiotic factors are the non-living parts of an environment
- For example: temperature, wind, humidity and soil pH
Biotic factors are the living parts of an environment
- For example: competition, predation and disease
Experiments can be carried out to investigate the effect of abiotic factors on the movement of animals
- Choice chambers and mazes are often used in these experiments and woodlice and maggots are commonly the model animals
A scientist called J. Cloudsley-Thompson carried out the first experiments on woodlouse behaviour
One of his experiments focused on the response of woodlouse to humidity
He used large choice chambers that were divided into two sections

Divide each choice chamber into two sections
- Add a fixed volume of distilled water to one side and a fixed volume of drying agent to the other
- This allows for the humidity to be controlled in each section
Insert gauze platforms into the choice chambers
- This keeps the woodlice at a safe distance from the water and drying agent
- Note that woodlice are able to move between sections
Divide the woodlice into two even-sized groups
- Drop the woodlice from group A into choice chambers kept in the dark
- Drop the woodlice from group B into choice chambers kept in the light
The woodlice can be dropped into the chamber using the hole in the lid so that they fall into the centre of the choice chamber
Record the position of the woodlice in each choice chamber after 15 minutes
- They should fall into the following categories: moving around, stationary on the dry side, stationary in the centre or stationary on the humid side
Repeat the experiment several times for all conditions

A significant percentage of the woodlice (in all groups) moved to the humid side
- This is a beneficial response as it helps to prevent water loss from the respiratory surfaces of the woodlice
The woodlice responded to humidity more actively when in the light
- This is advantageous - if the woodlice are subject to dry conditions during the day when they are more likely to dehydrate then they are even more likely to move towards humid conditions (under a stone, log etc)
The woodlice tended to stop moving when in humid conditions
- This means they are able to remain within favourable conditions that reduce water loss

In this experiment, the conditions that the woodlice were kept in prior to the experiment have not been stated
- If the woodlice were kept in dark or light conditions it could affect their response during the experiment
The behaviour of the woodlice was not observed during the experiment
- It can not be said if their behaviour was taxis (directional response) or kinesis (non-directional response) that randomly caused them to end up in the humid section