Adult dragonflies (Odonata: Anisoptera) are empirically the most successful predators on the planet, with each species hunting aerial prey in one of two discrete modes: sit-and-wait foragers that hunt from perches (perchers), and active, constantly flying foragers (fliers). Their long spiny legs come together to form a “capture basket” to grasp prey of various sizes. Each leg has two rows of chitinous projections (spurs), which differ among species in number, shape, angle, and spacing, particularly on the tibiae. However, the range of variation in leg spur morphology and the functional implications of these differences for prey capture remain largely unexplored. I compiled data from previously published behavioral studies and naturalist observations on the foraging mode and typical prey size for dragonfly species in the superfamily Libellulidae, which contains both perchers and fliers. I then employed light microscopy and microCT scans to quantify leg spur morphology (spur density, angles between spur rows, and spacing) between species to determine whether particular patterns of spur morphology can predict foraging behaviors. I found that spur density was a good predictor of foraging mode, and spur row angles were good predictors of prey size maximums. These results support the hypothesis that leg spurs play an important and informative role in prey capture and niche partitioning in dragonflies, paving the way for future research on the functional significance of spur morphology in the world’s greatest predator.
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