Journal of Comparative Physiology A

, Volume 198, Issue 6, pp 465–476

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

Original Paper

DOI: 10.1007/s00359-012-0723-4

Cite this article as:
Bohn, H.F., Thornham, D.G. & Federle, W. J Comp Physiol A (2012) 198: 465. doi:10.1007/s00359-012-0723-4


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 bicalcarataCamponotus schmitziInsect-plant interactionSwimmingGait analysis

Supplementary material

View video

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)

View video

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)

View video

Supplementary material 3 (AVI 888 kb)

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