Algae Can Use Their Flagella to Gallop and Trot

Researchers from the University of Cambridge have discovered that algae can use their flagella to gallop and trot like quadrupeds. The flagella are thin whip-like appendages that the single-celled algae use to navigate their watery habitats. They can achieve a variety of swimming gaits.

Dr Kirsty Wan of the Department of Applied Mathematics and Theoretical Physics (DAMTP) at the University of Cambridge is the first author of the paper. Wan says in a statement, "When I peered through the microscope and saw that the alga was performing two sets of perfectly synchronous breaststrokes, one directly after the other, I was amazed. I realised immediately that this behaviour could only be due to something inside the cell rather than passive hydrodynamics. Then of course to prove this I had to expand my species collection."

The researchers determined that the networks of elastic fibers which connect the flagella deep within the cell coordinate these diverse gaits. In the simplest case of Chlamydomonas, which swims a breaststroke with two flagella, absence of a particular fiber between the flagella leads to uncoordinated beating. In recent work from the same group, it was shown that nearby flagella can be synchronized solely by their mutual interaction through the fluid.

Professor Ray Goldstein, Schlumberger Professor of Complex Physical Systems at DAMTP, and senior author of the paper, says, "As physicists our instinct is to seek out generalisations and universal principles, but the world of biology often presents us with many fascinating counterexamples. Until now there have been many competing theories regarding flagellar synchronisation, but I think we are finally making sense of how these different organisms make best use of what they have."

A research paper on the findings was published here in the journal, PNAS.

Images: University of Cambridge

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