Journal of Comparative Physiology A

, Volume 198, Issue 6, pp 465–476 | Cite as

Ants swimming in pitcher plants: kinematics of aquatic and terrestrial locomotion in Camponotus schmitzi

  • Holger Florian BohnEmail author
  • Daniel George Thornham
  • Walter FederleEmail author
Original Paper


Camponotus schmitzi ants live in symbiosis with the Bornean pitcher plant Nepenthes bicalcarata. Unique among ants, the workers regularly dive and swim in the pitcher’s digestive fluid to forage for food. High-speed motion analysis revealed that C. schmitzi ants swim at the surface with all legs submerged, with an alternating tripod pattern. Compared to running, swimming involves lower stepping frequencies and larger phase delays within the legs of each tripod. Swimming ants move front and middle legs faster and keep them more extended during the power stroke than during the return stroke. Thrust estimates calculated from three-dimensional leg kinematics using a blade-element approach confirmed that forward propulsion is mainly achieved by the front and middle legs. The hind legs move much less, suggesting that they mainly serve for steering. Experiments with tethered C. schmitzi ants showed that characteristic swimming movements can be triggered by submersion in water. This reaction was absent in another Camponotus species investigated. Our study demonstrates how insects can use the same locomotory system and similar gait patterns for moving on land and in water. We discuss insect adaptations for aquatic/amphibious lifestyles and the special adaptations of C. schmitzi to living on an insect-trapping pitcher plant.


Nepenthes bicalcarata Camponotus schmitzi Insect-plant interaction Swimming Gait analysis 



We thank the Leverhulme Trust (F/09 364/G) and the German Research Foundation (Emmy-Noether Programme FE 547/1) for financial support of this study. We thank Charlie Ellington for giving us useful information for the thrust analysis, Karin Moll for advice on statistics, and Uri Grodzinski for his help with the behavioral analysis. Components of the KineMat MATLAB Toolbox by Christoph Reinschmidt and Ton van den Bogert were used for the three-dimensional kinematic analysis.

Supplementary material

Video 1: Natural swimming and foraging behavior of two C. schmitzi ants inside a pitcher of Nepenthes bicalcarata recorded in the field in Brunei. The ants can be seen going underwater along the pitcher wall, searching the remnants of captured prey at the bottom of the pitcher, re-surfacing by their buoyancy and swimming along the surface with open mandibles. Both ants are in the middle of a “swimming bout” consisting of cycles of swimming, diving and re-surfacing. Supplementary material 1 (MPG 8019 kb)

Videos 2 and 3: C. schmitzi worker swimming at the water surface, recorded at 100 Hz in an observation tank. Video 2: Side view; Video 3: Top view. Supplementary material 2 (AVI 934 kb)

Supplementary material 3 (AVI 888 kb)


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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.Department of ZoologyUniversity of CambridgeCambridgeUK
  2. 2.Plant Biomechanics Group FreiburgUniversity of FreiburgFreiburg im BreisgauGermany

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