The Respose of woodlice to light and dark

[unitedgirl7]

can anyone please help?because i need this for next week's assignment... thanks xxx

[theprof]

Golly, this takes me back.

Woodlice are negatively phototactic - they move away from a light source. They have this ability because they possess light receptors (ocelli) that are sensitive to levels of illumination.

In their natural environment, dark places are normally damp places whereas bright places tend to be drier and warmer. Because woodlice need humid conditions as well as dampness, they will move towards dark places which tend to be humid.

In dry conditions, woodlice and other isopods tend to randomly wander about. However, when they reach a humid, damp environment, they become sluggish and congregate in large numbers, often displaying a total lack of locomotion.

This is of course a taxis response rather than a kinesis.

I think that covers the gist of it.

Experimental set-ups to demonstrate this phototactic response are not that difficult to devise. The simplest involve placing a dozen or so woodlice on damp kitchen towel in a high-walled petri dish or similar under normal room illumination. A piece of black opaque card, black cloth or aluminium foil is placed over the top of one half of the dish.

Control experiments using normally lit containers holding the same number of woodlice need to be done at the same time. You would need to record the number of woodlice that have moved into the darkness for comparison after, say, a 30 minute period. Obviously, the woodlice would have to be introduced into the two containers at the same time.

Try covering another container completely with black card etc after introducing the woodlice. What difference does that make?

See if you can improve on my suggestions.

[unitedgirl7]

thanks very much for your answer it helped me a lot...but if any other people have suggestons can you please write to me? i have answered most of the question like the Aim of this Experiment, the Title,Method,Result table, but i don't know what to write for Conclusin and the Evaluation.... if anyone can help please write to me... thanks again xxx

[scientist9224]

Woodlice cannot survive in conditions subject to a lot of light or heat, if placed in a situation where these are the conditions they will be in fear of desiccation so will keep turning and changing, following new paths to try and find a way out of these stimuli and into the conditions they can survive in and are comfortable with such as moist dark areas. The closer they are to the light or heat source or the more they are subject to, the more turns they will make. This kind of movement is called kinesis.