The Effect of Temperature on the Motility of Euglena gracilis

  • Apaarjit Chahal
  • Kyle Chan
  • Christopher Lam
  • Animisha Parmar


This study investigated the effect of temperature on the motility of Euglena gracilis. A culture of E. gracilis was divided into four groups of test tubes and incubated at different temperatures (11℃, 17℃, 27℃, 34℃) for 60 mins. After incubation, the swimming speed of E. gracilis was measured under a compound microscope using a Dino-lite eyepiece camera. The results obtained, demonstrated a trend where the rate of forward swimming for E. gracilis increased as temperature increased until 27℃. The rate of forward swimming started to decline when the temperature surpassed 27℃. A one-way analysis of variance (ANOVA) resulted in a pvalue of 1.64 x 10-8indicating statistically significant differences in the results. The increase in speed at higher temperatures up to 27℃ may be attributed to increased metabolic activity, since 27℃ falls in the optimal temperature for E. gracilis growth (Buetow, 1962). The decrease in speed above optimal temperature may have been due to denaturation of the metabolic enzymes, hindering structures like the flagella (Humphries, 2013). Our prediction was met as the speed increased as temperature increased until E. gracilis’ optimal temperature, at which point the speed began to decline beyond the optimal temperature. We reject the null hypothesis that there would be no change in motility at varied temperatures and support the alternative hypothesis that there would be a change in motility.