Volvox barberi flocks, forming near-optimal, two-dimensional, polydisperse lattice packings
Abstract
Volvox barberi is a multicellular green alga forming spherical colonies of 10000-50000 differentiated somatic and germ cells. Here, I show that these colonies actively self-organize over minutes into "flocks" that can contain more than 100 colonies moving and rotating collectively for hours. The colonies in flocks form two-dimensional, irregular, "active crystals", with lattice angles and colony diameters both following log-normal distributions. Comparison with a dynamical simulation of soft spheres with diameters matched to the Volvox samples, and a weak long-range attractive force, show that the Volvox flocks achieve optimal random close-packing. A dye tracer in the Volvox medium revealed large hydrodynamic vortices generated by colony and flock rotations, providing a likely source of the forces leading to flocking and optimal packing.
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Cite
@article{arxiv.1803.03542,
title = {Volvox barberi flocks, forming near-optimal, two-dimensional, polydisperse lattice packings},
author = {Ravi Nicholas Balasubramanian},
journal= {arXiv preprint arXiv:1803.03542},
year = {2018}
}
Comments
7 pages, 5 figures