Mechanism for rapid passive-dynamic prey capture in a pitcher plant

Ulrike Bauer, Marion Paulin, Daniel Robert, Gregory P Sutton

Research output: Contribution to journalArticle (Academic Journal)peer-review

12 Citations (Scopus)
409 Downloads (Pure)

Abstract

Plants use rapid movements to disperse seed, spores, or pollen and catch animal prey. Most rapid-release mechanisms only work once and, if repeatable, regaining the prerelease state is a slow and costly process. We present an encompassing mechanism for a rapid, repeatable, passive-dynamic motion used by a carnivorous pitcher plant to catch prey. Nepenthes gracilis uses the impact of rain drops to catapult insects from the underside of the canopy-like pitcher lid into the fluid-filled trap below. High-speed video and laser vibrometry revealed that the lid acts as a torsional spring system, driven by rain drops. During the initial downstroke, the tip of the lid reached peak velocities similar to fast animal motions and an order of magnitude faster than the snap traps of Venus flytraps and catapulting tentacles of the sundew Drosera glanduligera. In contrast to these active movements, the N. gracilis lid oscillation requires neither mechanical preloading nor metabolic energy, and its repeatability is only limited by the intensity and duration of rainfall. The underside of the lid is coated with friction-reducing wax crystals, making insects more vulnerable to perturbations. We show that the trapping success of N. gracilis relies on the combination of material stiffness adapted for momentum transfer and the antiadhesive properties of the wax crystal surface. The impact-driven oscillation of the N. gracilis lid represents a new kind of rapid plant movement with adaptive function. Our findings establish the existence of a continuum between active and passive trapping mechanisms in carnivorous plants.
Original languageEnglish
Pages (from-to)11384-11389
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume112
Issue number43
Early online date5 Oct 2015
DOIs
Publication statusPublished - 27 Oct 2015

Keywords

  • plant movement
  • biomechanics
  • carnivorous plants
  • torsion spring
  • wax crystals

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