Burst escape speed is an effective and widely used behaviour for evading predators, with burst escape speed relying on several different morphological features. However, we know little about how behavioural and underlying morphological attributes change in concert as a response to changes in selective predation regime. We studied inter-correlated trait differentiation of body shape and burst-swim-mediating morphology in response to a habitat shift related reduction in burst escape speed using larvae of the dragonfly genus Leucorrhinia. Species in this genus underwent a well-known habitat shift from predatory fish lakes (fish-lakes) to predatory fish free lakes dominated by large predatory dragonflies (dragonfly-lakes) accompanied by relaxed selection on escape burst speed. Results revealed that species from fish-lakes that possess faster burst speed have evolved a suite of functionally inter-correlated traits, expressing a wider abdomen, a higher abdominal muscles mass and a larger branchial chamber compared to species from dragonfly-lakes. In contrast, populations within species did not show significant differences in muscle mass and branchial chamber size between lakes types in three of the species. High multi-collinearity among variables suggests that traits have evolved in concert rather than independently when Leucorrhinia shifted from fish lakes to dragonfly lakes. Thus, relaxed selection on burst escape speed in dragonfly-lake species resulted in a correlated reduction of abdominal muscles and a smaller branchial chamber, likely to save production and/or maintenance costs. Our results highlight the importance of studying integrated behavioural and morphological traits to fully understand the evolution of complex phenotypes.