Figure 10. Spontaneous fusion and fission for ring-like clusters with opposite vorticity.

(b) Emerging states for all swimmer types as a function of reduced self-propulsion velocities v/v₀—see Supplementary Movies 7–9. Each state is depicted in a sketch in panel a and can characterized by: (i) a non-rotating but translating coupled dimer, (ii) a counter rotating microswimmer chain orbiting around a ring of N=8 swimmers (iii) toddling and rotation, where the former rings exchange swimmers and translate, (iv) an emerging ring containing all N=10 swimmers as well as (v) collision induced and (vi) spontaneous fission of the ring-like clusters.