  Flagella are hair-like appendages attached to microorganisms that allow the
organisms to traverse their fluid environment. The algae Volvox are spherical
swimmers with thousands of individual flagella on their surface and their
coordination is not fully understood. In this work, a previously developed
minimal model of flagella synchronization is extended to the outer surface of a
sphere submerged in a fluid. Each beating flagellum tip is modelled as a small
sphere, elastically bound to a circular orbit just above the spherical surface
and a regularized image system for Stokes flow outside of a sphere is used to
enforce the no-slip condition. Biologically relevant distributions of rotors
results in a rapidly developing and robust symplectic metachronal wave
traveling from the anterior to the posterior of the spherical Volvox body.
