Figure 2. Viscosity and elasticity of the pure digestive fluid of N. rafflesiana.

(a) Shear viscosity η as a function of the shear rate (same mixing of fluids as in retention experiments). (b) Typical transient extensional viscosity η_E as a function of the extensional strain E, obtained from the thinning dynamics of a liquid filament in a capillary break-up geometry (see inset, the solid line materializes the elasto-capillary exponential regime giving the elastic relaxation time λ). The high increase of the extensional viscosity with strain is a signature of fluid elasticity. Arrows in (a) and (b) indicate the typical values of shear viscosity and extensional viscosity corresponding to insect motion in the fluid (∼40 s⁻¹ and with τ∼0.1 s the typical time scale for insect motion). Scale bars, 1 mm.