The effect of salinity on the number of food vacuoles formed over time in Tetrahymena thermophila


  • Jessica Alessandra
  • Sarah Choi
  • Taylor Kristmanson
  • Vicky Lee


Many organisms require a specific salinity in their environment to grow and reproduce
and changes to the salinity concentration can have drastic effects on their survival. The ciliate
Tetrahymena thermophila is typically found in freshwater environments, thus, the objective of
our experiment was to determine if salinity affects the number of food vacuoles present over
time. We hypothesized that higher salinity will negatively affect the number of food vacuoles
formed over time in T.thermophila. T.thermophila was placed in 0 mM, 5 mM and 100 mM NaCl
solutions and vacuole number was observed 20, 40 and 60 minutes into the treatments. We found
that the 0mM treatment group exhibited positive growth over time and the higher salinity
treatment groups exhibited no significant positive vacuole formation over time. T.thermophila
did not exhibit any vacuole growth in 100mM salinity treatment at any time point, indicating this
salinity is above their upper tolerance for vacuole formation. This significant difference in food
vacuole numbers allows us to reject the null hypothesis that higher salinity does not affect the
number of food vacuoles formed over time in T. thermophila.