Volvox barberi (Chlorophyceae) actively forms two?dimensional flocks in culture

Volvox barberi is a multicellular green alga forming spherical colonies of 10,000-50,000 differentiated somatic and germ cells. We observed that in culture, these actively self-organized just few minutes into flocks contained as many 100 moving rotating collectively for hours. The formed two-dimensional, irregular, active crystals, is, geometric lattices within which individual rotated separately. These groupings sometimes disassembled back quickly, but some cases, persisted over several Close inspection flock formation the presence tracer dye suggested colony rotations were producing vortices fluid medium range spanning multiple diameters, perhaps providing physical mechanism aggregation.