The tubule elongation in the water-water and water-oil experiments from The nematocyst's sting is driven by the tubule moving front

The movie shows the elongation of the tubule in water-only and in water-oil experiments. The activated capsule is marked by a dashed circle and the location of the water-oil interface by a yellow line. The clock shows the elongation time in seconds and turns red when the tubule completes its elongation.