Biomechanical analysis and computer simulations reveal Venus flytrap capture mechanisms

The Venus Flytrap (Dionaea muscipula) only needs 100 milliseconds to catch its prey. Once their leaves, which have been transformed into traps, have closed, the insects can no longer escape. Using biomechanical experiments and virtual flytraps of Venus, a team from the Freiburg Botanical Garden and the University of Stuttgart have analyzed in detail how the lobes of the trap move. Freiburg biologists Dr. Anna Westermeier, Max Mylo, Prof. Dr. Thomas Speck and Dr. Simon Poppinga and Stuttgart structural engineer Renate Sachse and Prof. Dr. Manfred Bischoff show that the plant trap Carnivorous is under mechanical stress. Furthermore, its three layers of tissue from each lobe have to deform according to a special pattern. The team has published their results in the magazine. procedures of the National Academy of Sciences.

The Venus flytrap diet consists mainly of crawling insects. When the animals touch the sensory hairs inside the trap twice in about 20 seconds, it closes. Scientists already knew about things like how the trap perceives its prey and how it differentiates potential prey from a raindrop that falls into the trap. However, the precise process of transforming the trap halves remained largely unknown.

To gain a better understanding of these processes, the researchers analyzed the interior and exterior surfaces of the trap using 3-D digital image correlation methods. Scientists often use these methods to examine technical materials. Using the results, the team built several virtual traps in a finite element simulation that differ in their tissue layer configurations and in the mechanical behavior of the layers.

Only the digital traps that were under tension showed the typical snap. The team confirmed this observation with dehydration tests in real plants: only well-watered traps can be closed quickly and correctly by releasing this pretension. Watering the plant changed the pressure in the cells and with it the behavior of the tissue. To close properly, the traps also had to consist of three layers of tissue: an internal one that contracts, an external one that expands, and a neutral intermediate layer.

Speck and Mylo are members of the University of Freiburg’s Living, Adaptive and Autonomous Energy Systems (livMatS) group of excellence. The Venus Flytrap serves as a model for a biomimetic demonstrator made of artificial materials that the group’s researchers are developing. Scientists use it to test the potential uses of material systems that have real characteristics: systems adapt to changes in the environment and obtain the necessary energy from this medium.