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Choice Chamber & Taxis Explorer

Explore how organisms respond to environmental stimuli using an interactive choice chamber. Adjust stimulus type and taxis strength to observe phototaxis, hygrotaxis, thermotaxis, and chemotaxis in real time. Apply chi-square analysis to test whether organisms show a statistically significant preference.

Controls

Taxis Strength+0.60
Repelled (−1)Positive taxis (attracted)Attracted (+1)
Number of Organisms30

Results

Elapsed: 0s · Total organisms: 0
A (Stimulus)0 (0.0%)
B (Control)0 (0.0%)
Dashed line = expected (50%)

Reference Guide

Types of Taxis

Taxis is a directional movement in response to a stimulus. Organisms move toward (positive) or away from (negative) the source.

  • Phototaxis - response to light. Drosophila are positively phototactic, planaria negatively.
  • Hygrotaxis - response to moisture. Pillbugs prefer damp environments.
  • Thermotaxis - response to temperature gradients.
  • Chemotaxis - response to chemical stimuli such as food odors.

Chi-Square Goodness of Fit

The chi-square test compares observed organism counts to the expected counts under the null hypothesis (equal distribution).

χ2=∑(Oi−Ei)2Ei\chi^2 = \sum \frac{(O_i - E_i)^2}{E_i}

If the calculated chi-square exceeds the critical value for the chosen significance level (typically 0.05), we reject the null hypothesis and conclude that organisms show a preference.

df=k−1χcrit2(1,0.05)=3.841\text{df} = k - 1 \quad \chi^2_{\text{crit}}(1, 0.05) = 3.841

Choice Chamber Design

A choice chamber is a container divided into sections with different environmental conditions. Organisms are placed in the center and allowed to move freely between chambers.

A two-chamber design has one stimulus side and one control side. A four-chamber design allows testing of multiple conditions simultaneously. The experiment runs for a set time, and final positions are recorded.

To ensure valid results, the number of organisms should be large enough (at least 20) and the observation period long enough for organisms to settle into a preferred chamber.

Kinesis vs Taxis

Taxis is a directional response where the organism moves toward or away from the stimulus. The direction of movement depends on the stimulus location.

Kinesis is a non-directional response where the organism changes its speed or turning rate based on stimulus intensity. Woodlice, for example, move more slowly in damp areas (orthokinesis), which causes them to accumulate there without actually navigating toward moisture.

This simulator models taxis behavior, where organisms have a directional bias toward or away from the stimulus source.