Contact angle measurements of droplets on the mandibles of antlions

Antlion larvae are fluid-feeding ambush predators that feed on arthropods trapped in their funnel-shaped pits built in sandy habitats; however, details are lacking about their feeding mechanism. Here we tested the hypothesis that the antlion, Myrmeleon crudelis, has adaptations that facilitate fluid feeding in sandy habitats. We measured contact angles of water droplets and used the capillary-rise technique to assess mouthpart wettability. A structural organization was discovered that provides a hydrophobic-hydrophilic wetting dichotomy that would simultaneously support self-cleaning and fluid uptake and is enabled by antiparallel movements of the maxillae. The mouthparts also are augmented by their material properties, including maxillae and mandible tips that are heavily sclerotized for piercing prey and mandibular teeth with resilin that would assist in preventing tooth breakage. Our findings provide insight on how antlion larvae have overcome the challenges of fluid feeding in sandy...