Carnivorous plant catapults prey with snap-tentacles
Biologists of the University of Freiburg describe a new capture mechanism
Carnivorous plants feature complex mechanisms to survive in habitats poor in nutrients: trapping systems help them to lure, catch, kill, and digest small prey animals (mainly insects) and to take up the resulting nutrients. Traps that move are termed ‘active’, and such active systems are currently being investigated in the Plant Biomechanics Group of the Botanic Garden Freiburg, led by Prof. Thomas Speck. In the PhD project of Simon Poppinga the researchers show for the first time the trapping action of the particular sundew Drosera glanduligera, which was accomplished in close collaboration with the private cultivators Siegfried and Irmgard Hartmeyer. The spectacular capture movement has been investigated biophysically, and the findings are published in the journal PLOS ONE.
Sundews are commonly known for their trap leafs being covered with sticky tentacles to which small prey animals stick to and become wrapped within minutes up to hours. The Round-Leaved Sundew Drosera rotundifolia, which is native to nutrient-poor bogs also in the Black Forest, possesses such a flypaper-trap. Additionally to these glue-tentacles, Australian Drosera glanduligera features non-sticky snap-tentacles that bend towards the trap centre within 75 milliseconds after mechanical stimulation, which is faster than the snap-trapping action of the famous Venus Flytrap. The function of these tentacles was subject to speculation until now. It could be shown that the snap-tentacles catapult incautious prey animals onto the sticky trap leaf, and that this sundew hence possesses a combined catapult-flypaper-trap.
Carnivorous plants enjoy great popularity worldwide. Although the trapping mechanism described here can surely be termed one of the most spectacular plant movements, only few persons will be able to see it with their own eyes due to the very tough cultivation and short life span of the plant. All the others can follow a documentary about this research project on YouTube: http://www.youtube.com/watch?v=Zzi3XDQs-i0
Poppinga, S., Hartmeyer, S. R. H., Seidel, R., Masselter, T., Hartmeyer, I., Speck, T. (2012) Catapulting tentacles in a sticky carnivorous plant. PLOS ONE (in press.). doi: 10.1371/journal.pone.0045735
Prof. Dr. Thomas Speck
Plant Biomechanics Group
Botanic Garden of the University of Freiburg