Measurement of cell velocity distributions in populations of motile algae

V. A. Vladimirov, M. S.C. Wu, T. J. Pedley*, P. V. Denissenko, S. G. Zakhidova

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)


The self-propulsion of unicellular algae in still ambient fluid is studied using a previously reported laser-based tracking method, supplemented by new tracking software. A few hundred swimming cells are observed simultaneously and the average parameters of the cells' motility are calculated. The time-dependent, two-dimensional distribution of swimming velocities is measured and the three-dimensional distribution is recovered by assuming horizontal isotropy. The mean and variance of the cell turning angle are quantified, to estimate the reorientation time and rotational diffusivity of the bottom-heavy cell. The cells' phototactic and photokinetic responses to the laser light are evaluated. The results are generally consistent both with earlier assumptions about the nature of cell swimming and quantitative measurements, appropriately adjusted. The laser-based tracking method, which makes it possible to average over a large number of motile objects, is shown to be a powerful tool for the study of microorganism motility.

Original languageEnglish
Pages (from-to)1203-1216
Number of pages14
JournalJournal of Experimental Biology
Issue number7
Publication statusPublished - Mar 2004


  • Chlamydomonas nivalis
  • Laser-based tracking
  • Motility
  • Swimming direction
  • Unicellular algae
  • Velocity distribution

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology
  • Insect Science


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