Collectively moving filaments in oil suspensions of the nematode T. aceti*

Previous research indicates that the nematoda Turbatrix aceti, commonly known as vinegar eels, can synchronize their body oscillations under favorable conditions, such as the droplet's contact angle ( θ > 68°) to produce metachronal waves similar to the one that sports fans create on the stadiums. 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. We measure the oscillation frequency inside and outside the oil, the number of filament splits, the density of nematodes per region, and how fast the filaments are advancing. We find that the nematodes in less viscous oils were able to spread out faster and create interlocking filaments. In comparison, nematodes in more viscous oils only spread individually without creating collectively moving filaments. Their travel distance was smaller than the one of collective filaments in low viscosity oil. Further research is necessary to determine whether other factors such as oil density may have contributed to the results.