Locomotory efficiency and potential has been studied in three species of the waterboatman Notonecta in relation to the predation strategies of these bugs.Morphometric analysis, estimating likely relative drag forces, mechanical advantages of the swimming legs and leg length/body length ratios allowed an estimation of locomotory efficiency of the three bugs on the basis of their structural features.A study of the effect of activity on the respiration rate investigated how the predators locomotory abilities were reflected in their physiology.Finally, the relative locomotory abilities of the three predators were compared behaviourly be examining pursuit and attack success after free swimming prey in simple and complex environments.Differences were found between the three predator species which were consistent for the three experimental methods and these were successfully related to the predation strategies and habitat selection of the bugs.