Product Instructions: Choice Chambers
These choice chambers have been especially designed to allow observation of organisms as
they choose from up to four different conditions.
Each dish consists of a clear plastic lid, and a base which is available in a range of colours.
5x Clear
5x Blue
5x Green
5x Red
5x Purple
1 of each
EN120975
EN120980
EN120985
EN120990
EN120995
EN120900
The base is divided into four chambers of equal size. Each chamber can store a substance to
create a unique environment for that chamber. For example, a desiccant could be placed in
to create a dry chamber, and a damp sponge could be placed in another to create a humid
chamber.
The lid has recessed segments, into which a cover of some sort can be placed to modify the
environment of a particular chamber. For example, thick black card could be used to create a
dark environment.
Also in the lid is an 18mm diameter hole in the middle into which organisms can be dropped.
This means the environments of the four chambers do not need to be disturbed by lifting the lid
to place the organisms in.
Note that the lid and base have a lip that ensures the recessed segments of the lid line-up
exactly with the chambers in the base. The lid therefore can only be placed on the base properly
when correctly orientated.
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Product Instructions: Choice Chambers
Setting up the Choice Chamber
1.Place your chemicals (e.g. desiccant) and other materials in the chambers of the base to
create your condition gradient.
2.Place a layer of mesh over the base (available separately, Timstar code EN120905). This
gives the organisms a surface to move on without coming into contact with the chemicals
or materials. It is permeable which ensures organisms are exposed the condition gradient
you’ve set up. The mesh should not touch any of the chemicals or material placed in the
chambers.
3. Place the lid on top, trapping the layer of mesh.
4.Finally, place any filters you wish (e.g. black card) into the sections on the lid to complete
your condition gradient.
4
3
2
1
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Product Instructions: Choice Chambers
Creating Condition Gradients
It is important that a “condition gradient” is setup between the chambers. This is done by creating
opposite conditions in opposing chambers. For example, when investigating an organism’s
response to a humidity gradient (from wet to dry) a damp sponge would be placed in one
chamber, and a desiccant in the other.
Damp sponge
Desiccant
Allow to equilibrate before introducing organisms.
Humidity Gradient
Anhydrous calcium chloride (Timstar code CA1856) is a very effective and fast active
desiccant. However, it is also an irritant and reacts exothermically with water, and can cause
it to boil. If using this, care should be taken to minimise dust, avoid contact with skin, and
wash hands with plenty of running water if need be. Consult CLEAPSS Hazcard 19A for more
information.
A safer alternative is self-indicating silica gel. Two varieties are available. The variety that goes
from orange-to-colourless (Timstar code SI5336) has no associated hazards. The blue-to-pink
type (Timstar code SI5338) is impregnated with cobalt(II) chloride, which is hazardous. If using
this, wear gloves, and minimise dust. Consult CLEAPSS Hazcard 86 for more information.
Water should be used to create the humid end of a humidity gradient. Using a piece of sponge,
cotton wool or absorbent paper soaked in water will help prevent water getting onto the mesh or
into other chambers if the apparatus is knocked or otherwise moved.
Cobalt chloride paper can be used to check how well the humidity gradient is established
(Timstar code TP7000 10 books, TP7003 100 books).
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Product Instructions: Choice Chambers
Light Gradient
The lid of the choice chamber is transparent, so sections can be illuminated using natural or
artificial light.
Layers of tracing paper can be placed over chosen sections to make a dark chamber, or black
card can be used to create an almost “blacked out” chamber.
Ensure when illuminating choice chambers that the light source is not too intense, especially if it
is sunlight or an incandescent source. The clear plastic lid will act like a greenhouse, and so the
chamber will heat up quickly.
Colour Gradient
Acetate sheets of different colours can be used to make different colours of light.
For example, some organisms may prefer green light if they’re used to it being filtered by the
leaves of trees above them, or brown light if they live beneath fallen foliage.
Further Resources
Nuffield Foundation, Practical Biology
Using a Choice Chamber to Investigate Animal Responses to Stimuli
http://www.nuffieldfoundation.org/practical-biology/using-choice-chamber-investigate-animalresponses-stimuli
Nuffield Foundation, Practical Biology
Investigating the Response of Calliphora Larvae to Light
http://www.nuffieldfoundation.org/practical-biology/investigating-response-calliphoralarvae-light
www.timstar.co.uk [email protected]
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Product Instructions: Choice Chambers
Filter Template
Print or photocopy this sheet to cut out black card or filters to place on top of the choice chamber.
www.timstar.co.uk [email protected]
01270 250459 01270 250601