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
habitats, which likely contributed to their success and widespread
distribution.