Worm drop experiment : Dripping dynamics and tunable flow behaviour of active tangled worm assemblages

California blackworms (Lumbriculus variegatus) have a highly flexible and slender polymer-like body. Collectively, they form entangled blobs and exhibit viscoelastic properties. We investigate the fluid-like behavior of these worm collectives. Taking inspiration from the dripping faucet experiment with ants (1998) and the pitch drop experiment (1984), we set up a “leaky faucet”-like experiment where the worms flow under the influence of gravity through a funnel. To understand how geometry influences the flow dynamics, we systematically vary the funnel outlet diameter and neck length, quantifying their effects on droplet formation parameters such as pinch-off time and drop length. Beyond geometric control, we further modulate the collective’s effective viscosity by tuning the activity of individual worms. By applying external stressors like electrical stimulation to enhance activity and ethanol immersion to suppress it, we alter the bulk flow behavior of the worm “fluid.” To link these macroscopic flow properties to microscopic activity, we subject individual worms to the same stimuli and extract measures of their motility (slope of mean square exponent) and elasticity (relaxation time, τ, from end-to-end distance fluctuations). These activity metrics provide a quantitative bridge between individual behavior and collective rheology. Our study enhances the understanding of complex flow behaviors in living active fluids and the mechanisms underlying their tunable fluid mechanical properties.