Filaments of collectively moving nematode T. aceti in viscous fluids

Previous research indicates that under favorable conditions the nematode Turbatrix aceti swimming in water, can synchronize their body oscillations, to produce collectively beating metachronal waves at the borders. It is unknown whether these nematodes can still synchronize their motion in high viscosity fluids. We study the collective motion of nematodes in oils of different molecular weight and viscosity. We find that contrary to the water suspensions, nematodes in oil form collectively propagating filaments. The properties of this filaments such as the oscillation frequency, the number of splits, and their velocities, depend on the viscosity of the oils. We find that the nematodes in less viscous oils were able to spread out faster and create interlocking filaments, reminiscent of a network of neurons. In comparison, nematodes in more viscous oils only spread individually without creating filaments.