Morphing structures in the Venus flytrap

Venus flytrap is a marvelous plant that intrigued scientists since times of Charles Darwin. This carnivorous plant is capable of very fast movements to catch insects. Mechanism of this movement was debated for a long time. Here, the most recent Hydroelastic Curvature Model is presented. In this model the upper leaf of the Venus flytrap is visualized as a thin, weakly curved elastic shell with principal natural curvatures that depend on the hydrostatic state of the two surface layers of cell, where different hydrostatic pressures are maintained. Unequal expansion of individual layers A and B results in bending of the leaf, and it was described in terms of bending elasticity. The external triggers, either mechanical or electrical, result in the opening of pores connecting these layers; water then rushes from the upper layer to the lower layer, and the bilayer couple quickly changes its curvature from convex to concave and the trap closes. Equations describing this movement were derived and verified with experimental data. The whole hunting cycle from catching the fly through tightening, through digestion, and through reopening the trap was described.