Life at the microscale is constantly on the move. However static a glass of seawater, lump of soil or drop of blood appears to the naked eye, magnified several dozen times we find myriads of microscopic lifeforms buzzing with activity. At first sight, their motion appears haphazard, chaotic, or disorganised. However, decades of research have shown that the movement of microbes has been fine-tuned through the evolutionary pressures of searching for nutrients, avoiding toxins or escaping microscopic predators. These migratory responses to environmental cues are known as chemotaxis.

Swimming E. coli cells under a microscope. Courtesy of Howard Berg (www.rowland.harvard.edu).

Since the development of microscopy biologists have uncovered a great deal about…


Movement, exploration and search are ubiquitous behaviours among many organisms. Low on the tree of life, bacteria have evolved the ability of chemotaxis to navigate landscapes of concentrations to find nutrients or to avoid toxins. As another example, pigeons have an exceptional ability to navigate based on visual landmarks, among other cues, to find their way back home. Finally, many mammals have evolved a complex network of neurons including, but not limited to, grid cells and place cells to represent and search physical spaces, or perhaps even the space of memories.

Illustration of an animal searcher (fly) navigating a heterogeneous environment (e.g. odour landscape) based on a finite perceptual horizon.

A common feature among many animal searchers is using…

Adam Gosztolai

Mathematician, Postdoctoral fellow in Neuroscience at EPFL @AGosztolai

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